The match ended on something of a sour note, however, as Daniel Potts was stretchered off having received oxygen on the pitch for around 10 minutes.
You can read how a remarkable match unfolded with Sports Mole below.
6.45pmGood evening! Welcome to Sports Mole's coverage of tonight's match between Arsenal and West Ham! Let's get straight down to business.
6.47pmWe'll start by looking at Arsenal, and they are in desperate need of a win tonight. Their 2-1 loss to Chelsea at the weekend left them seven points behind North London rivals Tottenham Hotspur in the race for fourth.
6.49pmManager Arsene Wenger would reject claims that tonight is a "must-win" match, but three points would make the table look a lot healthier for them and, if they are going to mount a serious challenge for fourth, they need to win these sorts of games, especially when it is their game in hand.
6.51pmThe result of this one could depend largely on which Arsenal turn up, however. Their first half performance against Chelsea was poor while their second half performance was much better. Wenger will be striving for a bit more consistency from his side as they certainly have the players to cruise to a comfortable victory tonight.
6.53pmWest Ham will be fully aware that they are catching Arsenal at a good time, however. Manager Sam Allardyce knows that his side are underdogs tonight, but his style of football could upset Arsenal - as it has in the past - and could be their key to success tonight.
6.55pmWhile noting that the Gunners aren't in the best form, we should also recognise that West Ham aren't exactly setting the world alight either. The Hammers have failed to score in their past five away games, and they have picked up just eight points on their travels so far this season. Couple this with just one win in nine in all competitions and you'd have to say that the odds are against Allardyce's men tonight.
6.57pmThe Hammers have already received some good news today, however, as defender Guy Demel has signed a new contract at the club.
6.59pmSpeaking of Guy Demel, he is included once again in West Ham's starting lineup this evening. There are, however, four changes for West Ham as Matty Taylor, Jack Collison, Ricardo Vaz Te and Carlton Cole return.
7pmWEST HAM XI: Jaaskelainen; Demel, O'Brien, Reid, Tomkins; Noble, Taylor, Nolan, Collison; Vaz Te, C Cole
7pmWEST HAM SUBS: Henderson, Potts, Diarra, Diame, O'Neil, J.Cole, Jarvis
7.01pmArsenal, meanwhile, have made two changes of their own as Lukas Podolski and Aaron Ramsey replace Abou Diaby and Francis Coquelin, which means that Olivier Giroud stays up front for the Gunners.
7.02pmARSENAL XI: Szczesny; Sagna, Mertesacker, Vermaelen, Gibbs; Ramsey, Wilshere; Walcott, Cazorla, Podolski; Giroud
7.03pmARSENAL SUBS: Mannone, Koscielny, Jenkinson, Santos, Frimpong, Oxlade-Chamberlain, Arshavin
7.06pmSo, interesting changes from both sides. Wenger has opted to bring in Ramsey and drop Wilshere back into the centre midfield role, naming an attacking trio of Walcott, Podolski and Cazorla to support Giroud. This will allow Cazorla to revert to his favoured position just behind the striker, while I can only presume that Diaby's injury woes are the reason behind Wenger not naming him in the lineup. Two matches in the space of three days may have been too much.
7.08pmJoe Cole's absence is probably for the same reason as he looks to return to full fitness. Carlton Cole will be looking to get about the Arsenal back two as he has more height and power than Vermaelan and more pace than Mertesacker. Vaz Te's trickery could also prove problematic for Mertesacker, who is not the quickest across the ground.
7.10pmThere is no place in the starting lineup for Diame either, despite the midfielder scoring West Ham's only goal in the reverse fixture earlier this season, a macth which ended 3-1 to the Gunners.
7.12pmThat match was the latest in a fairly long line of disappointing results for West Ham against today's opponents. They haven't beaten Arsenal since 2007, when Bobby Zamora scored the game's only goal. Of Arsenal's 16-man squad that day, only Diaby has been named in today's squad.
7.14pmOverall, the club's have faced each other 110 times, with Arsenal triumphing in 51 of those and West Ham in 27. A win today would bring up their 100th home point against the Hammers.
7.16pmNeither manager will be worried about the past tonight, however. They will be fully focused on the match and what it could do for their club. I've already mentioned Arsenal's position - a win would bring them back within back to within four points of a Champions League spot - but what about West Ham?
7.18pmWell, the Hammers could move back into the top half with a win tonight, leapfrogging Stoke City and Sunderland into 10th place. For the pessimistic fans looking down the table rather than up it, a win would also put them a healthy 11 points clear of the relegation zone.
7.20pmThe man in the middle for today's match will be Andre Marriner, who last took charge of Arsenal during their 1-0 loss to Norwich City and West Ham in their 3-1 loss to Spurs.
7.22pmMarriner also took charge of the match between these sides earlier in the season which, as mentioned earlier, ended 3-1 to Arsenal courtesy of goals from Giroud, Walcott and Cazorla.
7.24pmThis match isn't the only one on tonight, remember. We also have the second leg of the League Cup semi final between Swansea and Chelsea. The Swans currently have a 2-0 aggregate lead, and the winner will go on to face League Two side Bradford in the final at Wembley.
7.26pmYou can follow live coverage of that match with my good friend Pascal Lemesre here, but I will also be keeping you updated with the score as we progress tonight!
7.28pmWe're just over 15 minutes from kickoff here tonight, and Arsenal fans will surely be seeing this as a chance to get their season back on track.
7.30pmThey may not be in great form themselves, but they are coming up against a team in even worse form and, perhaps more importantly, a team with a poor away record so far this season.
7.32pmThe Gunners haven't been at their best in front of their own fans either, however. If the table consisted of just home matchs played, they would be 12th! They need to improve that in order to squeeze their way into fourth - missing out on Champions League football may be the final straw for many fans.
7.34pmArsene Wenger has undoubtedly been the club's greatest ever manager, surpassing even the legendary Herbert Chapman, but the facts remain that he hasn't won a trophy since 2005 and their league performances are getting worse. The guarantee of Champions League football has softened the blow of missing out on a trophy somewhat - although there is no feeling quite like winning a trophy - but what will happen with no silverware and no European football? Wenger's job could very well be under threat.
7.35pmPREDICTION: We're 10 minutes from kickoff at the Emirates, and that can mean only one thing - prediction time! Both sides come into the match in poor form, but I just can't see West Ham getting anything out of this one. I'm going to go for a home win, either 2-0 or 3-0 to Arsenal.
7.38pmYou can never be too sure about Arsenal's defence - even the usually-reliable Thomas Vermaelen has been shaky this season - but I think they will be able to keep a clean sheet today.
7.40pmThe players are in the tunnel, we're five minutes from kickoff in a huge match for Arsenal. They really can't afford to drift much further away from the Champions League places!
7.42pmInteresting little stat: West Ham's last win over Arsenal was the Gunners' first loss at the Emirates Stadium. Since then they haven't even scored at this ground, though.
7.44pmThis match was originally scheduled for Boxing Day, but couldn't be played then due to a railway strike. The fans have had to wait a while for this one but hopefully it will be worth the wait!
7.45pmRight, we're nearing kickoff here. The players have line up and it will be West Ham who get us underway.
0 minAnd we're off! Nolan immediately tries to thread a ball through early on but the attack is rebuffed by the Arsenal defence.
1 minThere are a lot of empty seats in the Emirates at the moment. Hopefully they will begin to fill up soon, but the snow, Arsenal's poor form and perhaps even the recent row of ticket prices could have taken a toll.
2 minRamsey puts in a late, heavy tackle on Noble. The Welshman is very lucky not to be booked. It doesn't matter what minute it came in, that was yellow card worthy.
4 minWalcott races down the right and has a chance to put a ball in but the England international is off balance and can't get enough on his cross, allowing West Ham to clear.
6 minCollison overruns the ball and goes in heavily on Wilshere, who goes down in a crumpled heap. The ref waves play on and Arsenal eventually kick the ball out. Quite a nasty-looking challenge from Collison, particularly on the injury-prone Wilshere.
8 minArsenal have a corner after West Ham give the ball away in a dangerous position. Walcott gives it to Sagna but the right back is forced out wide and wins the corner, which comes to nothing.
9 minSHOT! The first shot of the day goes West Ham's way as Vaz Te rises highest in the box, but his header is quite tame and goes wide.
11 minHalf chance for Arsenal as Giroud gets away from his man inside the box after some nice build-up play from the Gunners. He tries to pull it back to someone in a more central position, but his pass only finds a West Ham man.
13 minCHANCE! A fine pass by Wilshere finds Walcott racing through into the box, but Winston Reid gets back to put in a brilliant tackle. Walcott, and the whole ground, think that Arsenal have a corner but the lineman points for a goalkick!
15 minThis is a good spell for Arsenal, but the Hammers are holding firm at the moment. Gibbs tries to find space to shoot on the edge of the box but his effort is blocked.
16 minCLOSE! A ball comes into the Arsenal box from a free kick and is only cleared as far as Matt Taylor, whose shot from the edge of the box is deflected just over and onto the roof of the net.
18 minGOAL! Arsenal 0-1 West Ham (Jack Collison)
18 minWest Ham take the lead! Arsenal really didn't learn from their earlier mistake, again heading a set piece, this time a corner, onto the edge of their own box. Jack Collison is waiting there in acres of space and he smashes the ball past a helpless Szczesny. Very good goal, but poor defending from Arsenal.
20 minThat's been the story of recent weeks for Arsenal and, yet again, they will have to come from behind if they want to win this one. They have had the better of the match so far but a momentary lapse of concentration in defence was emphatically punished.
21 minGOAL! Arsenal 1-1 West Ham (Lukas Podolski)
21 minThe Gunners hit straight back with a great strike of their own. Sagna has it down the right and begins to work it across the field. The final pass comes from Wilshere, but Podolski should take all of the credit as he hammers it into the bottom corner from the edge of the box. Two goals of the highest quality and it's 1-1!
24 minCHANCE! West Ham have a chance to regain their lead as Vaz Te beats Sagna in the air from a corner, but it is just too high for him and the ball ends up way over the bar. Not an easy chance by any means but a chance nonetheless.
26 minBoth sides look like they will create a chance everytime they have the ball at the moment. Arsenal fail to do so, however, as a passing move ends with the ball going out for a West Ham throw in.
29 minWalcott shows tremendous pace down the right before whipping in a dangerous cross into the fabled corridor of uncertainty. Tomkins pulls off a brilliant piece of defending to get it clear, however, and West Ham survive.
31 minGibbs is down and hurt, and he will receive treatment off the field. Meanwhile, Cazorla bears down on the Hammers' defence but is dealt with well by O'Brien, who concedes a corner.
33 minWilshere has a chance to cross but instead chooses to cut inside and shoot. He is clipped on his way through but, admirably, stays on his feet before scuffing his shot and asking for the foul anyway. Andre Marriner says no.
35 minOFF THE LINE! Great build-up play again for Arsenal and they really should be in front. Gibbs and Giroud link up to give the ball to Podolski who is through on goal about seven yards out, but he has to stretch to make contact and can't get enough on his effort as a defender gets back to clear it off the line.
37 minArsenal are knocking on the door at the moment and I'd be surprised if they didn't find a way through here, perhaps even before half time.
39 minSHOT! Giroud picks out Podolski with a long ball and the German knocks it down to Cazorla, who drags his long range effort wide of the target.
40 minOFF THE LINE! West Ham come so close to regaining the lead! Demel puts an early ball into the box which Sagna fails to clear, allowing Cole through on goal. He tries to lift it over the onrushing Szczesny, but an Arsenal defender - I think it's Vermaelen - gets back in time to clear it off his own goalline.
42 minVermaelen is still reeling from that clearance, it looks like he and Ramsey collided in their efforts to clear the ball.
45 minWe will have three minutes of stoppage time at the end of this half. Can anyone find a breakthrough in that time?
45+1 minArsenal have a freekick in a very dangerous position right on the edge of the West Ham box after Nolan brought down Cazorla.
45+3 minCazorla's freekick comes close but West Ham eventually get it clear and now they have one of their own in a good position now...
45+3 minIt slithers all the way through to the keeper at the near post, and Szczesny gathers comfortably.
45+3 minHALF TIME: Arsenal 1-1 West Ham
8.37pmThis one is very delicately poised! The Gunners have had the better of the half, but West Ham have come closest to getting a second through Cole's effort that was cleared off the line. I'm still expecting Arsenal to win this one, but they have looked fragile at the back at times so I wouldn't be surprised if West Ham could nick a goal as well.
8.39pmLet's not forget that the Gunners have also had one cleared off the line, however. Podolski probably should have scored, but it was great defending to deny the German a second of the match.
8.41pmBoth goals have been a joy to behold as well. Collison left Szczesny no chance as he thumped the ball past the Arsenal keeper, while Jaaskelainen was left similarly helpless by Podolski's effort.
8.43pmNeither manager will be too disappointed at the break. Arsenal are playing well and, if they carry on as they have been, should win this one. Wenger won't be happy at the defending for West Ham's goal but since then they have been the better side. He may also want to tighten his defence up to stop the Hammers' rare but dangerous attacks.
8.45pmSam Allardyce will also be happy enough with his side's performance. He would've taken this scoreline at the halfway stage and his side have had chances to nick another one. If the Hammers can remain tight at the back then they will fancy their chances of getting a goal and winning this one. Even if they don't manage that, though, a draw at the Emirates would still be regarded as a fine result.
8.50pmThe Gunners dominated possession during that first half, enjoying 73% of it. They are the first side out ahead of the second period as they look to get a goal to go ahead here.
45 minWe're back underway!
45 minCHANCE! So nearly an own goal less than 20 seconds into the half! Theo Walcott races down the right and puts in another dangerous low ball towards Wilshere. Tomkins slides in and puts it out for a corner, however, diverting it inches wide of his own post. Great defending.
47 minGOAL! Arsenal 2-1 West Ham (Olivier Giroud)
47 minGreat start to this half for Arsenal! Walcott's corner originally looks like a poor cross, but perhaps it was planned? Giroud meets it at the near post and pokes it past Jaaskelainen to give the hosts the lead!
49 minThat is just what Arsenal needed at the start of this half, and West Ham now have an uphill battle to get back on level terms. The Gunners are very much in the ascendancy.
51 minCHANCE! A magical, sublime pass from Cazorla across field finds Walcott who looks to have got away from his man, but the ball just gets stuck under his feet and he is forced to try and cross it. Tomkins is there to clear it away, however.
52 minGOAL! Arsenal 3-1 West Ham (Santi Cazorla)
53 minBeautiful football from Arsenal. Some lovely build-up play sees Giroud find Podolski in the box who, in turn, finds Cazorla who flicks it past Jaaskelainen. What a start to this half!
54 minGOAL! Arsenal 4-1 West Ham (Theo Walcott)
54 minArsenal are rampant at the moment! West Ham are defending ridiculously high up the pitch and one ball beats their whole defence. Giroud leaves it for Podolski and the German finds Walcott coming in at the back post, and he makes no mistake.
56 minGOAL! Arsenal 5-1 West Ham (Olivier Giroud)
57 minThis is amazing stuff! Whatever Wenger said at half time has most certainly worked and Podolski is again heavily involved. This time he is found by Wilshere's pass before sending a ball into Giroud, who pokes it past Jaaskelainen again! Four goals in just over 10 minutes at the start of this half, Arsenal are cutting through West Ham like a hot knife through butter!
57 minARSENAL SUB: Off goes Thomas Vermaelen for Laurent Koscielny.
60 minPhew, I'm just catching my breath after that spell! Arsenal are still coming forward and West Ham may have to go for damage limitation here.
62 minWEST HAM SUB: Off goes Reid for Alou Diarra, while Collison is also replaced by Daniel Potts.
64 minPodolski has become the first player to have got three assists in a single game this season. He has been instrumental in all but one of the goals for the Gunners tonight.
65 minSHOT! Walcott looks to double his personal tally from a free kick, but in the end it's a fairly comfortable save for Jaaskelainen.
68 minWest Ham now have a freekick in a dangerous position but, with Noble over it, it comes to nothing.
68 minCHANCE! Arsenal break away again and Walcott has two men in the middle to find, but his cross is blocked by Demel! That would've been a certain sixth if he had managed to find either of his teammates.
70 minARSENAL SUB: Podolski, who has assisted three and scored one today, is replaced by Andre Santos.
70 minWEST HAM SUB: Diame is also going to come on as the Hammers look to avoid conceding anymore goals.
72 minARSENAL SUB: Giroud is the next to make way having scored twice today. It doesn't get any easier on the tired legs of West Ham, however, as he is replaced by Oxlade-Chamberlain.
73 minWest Ham have more immediate troubles, however, as Potts is being stretchered off. They've already made all three subs, so could be forced to play out the remainder of this one with 10 men. The phrase 'bad to worse' springs to mind.
76 minPotts is still down on the pitch and this one looks serious. Expect plenty of stoppage time.
79 minThe stoppage continues and Potts is being fitted with a neck brace and given oxygen. It looked like a standard collision but is obviously a lot more serious than first thought.
81 minHe is finally being stretchered off now to a standing ovation around the ground. He's been down for almost 10 minutes now, we give him our best wishes and hopefully it's not as serious as it looks.
83 minWe're back underway after that lengthy stoppage and Arsenal are straight back on the attack. If you think that they will show any mercy to the 10 men of West Ham, think again.
86 minThere's been a little lull in proceedings here at the Emirates following that injury, but an update on the condition of Potts: The defender is still unconcious and has been taken to hospital.
88 minUPDATE: An update from the League Cup tie and it's still 0-0, although Chelsea have been reduced to 10 men after Hazard had an altercation with a ball boy! Yes, you read that right!
90 minThe Potts injury has had a big effect on the amount of stoppage time we'll have here. The fourth official's board says 12 minutes.
90+1 minWilshere looks to add a spark to an otherwise dull end to the game by bursting through the middle, but he is eventually crowded out.
90+2 minCHANCE! Walcott should probably do better there as Sagna's cross finds him in space, but his header trickles well wide of the post.
90+4 minPOTTS UPDATE: Some good news to report on Potts, who has regained consciousness in the ambulance.
90+5 minOxlade-Chamberlain looks to get his name on the scoresheet by firing an effort goalwards, but it is blocked by Tomkins and comes back off Oxlade-Chamberlain and out for a goal kick.
90+7 minSHOT! Cazorla fires goalwards but it is another fantastic block to deny Arsenal a sixth. It didn't look like Jaaskelainen was getting to that one.
90+8 minWest Ham will just want to hear the whistle now and you'd think that Arsenal wouldn't be angry at not playing the full 12 minutes either. Rules are rules, however, and we must play them.
90+9 minTo be fair to the Hammers, though, they are still marauding forward whenever they get the chance. Guy Demel is the latest to attack, but he can't get a cross in.
90+11 minSHOT! We're past the 100 minute mark, something that doesn't happen often in football. To celebrate, Andre Santos looks to hammer one home from range but he drags it wide.
90+12 minFULL TIME: Arsenal 5-1 West Ham
9.49pmThere you have it, quite an amazing match comes to an end after 12 minutes of added time. The first half was good to watch, but the real entertainment came in the first 10 or so minutes of the second half as Arsenal scored four quickfire goals to secure the win.
9.51pmThe thrills of seeing six goals were countered by the sadness of seeing Daniel Potts receive 10 minutes of treatment on the field, however, and we wish him all the best.
9.53pmArsene Wenger will be delighted after that one. His side move back to within four points of North London rivals Tottenham in the race for the final Champions League spot and their second half performance - at least the first 15 minutes of it - looked like the Arsenal teams of old. They ripped West Ham apart in a way that even 'the Invincibles' would've been proud of.
9.57pmAllardyce, meanwhile, will be furious at how his side capitulated at the start of that second half. Arsenal played some scintillating stuff, but West Ham made it pretty easy for them to do so! At half time they were still very much in the game but 10 minutes after the restart they were forced into damage limitation mode!
9.58pmAn update on the other match tonight, and Swansea have made it through to their first ever League Cup final by drawing 0-0 with Chelsea. They will face Bradford in the final, but the real story of the night from the Liberty Stadium came when Eden Hazard was sent off for kicking a ballboy who had decided to lie on the ball instead of returning it to Chelsea! Incredible scenes, but congratulations to Swansea.
10pmRight, that's it from me tonight! Thanks for joining Sports Mole on a remarkable night of football that saw Arsenal move four points behind fourth-placed Spurs. Once again, we give our best wishes to Daniel Potts who suffered a horrible injury. I leave you with tonight's match report and be sure to stick around for analysis which will be on site within half an hour.