Read below to see how the action unfolded in North London.
6.46pmHello, and welcome to Sports Mole's live coverage of the match in the EFL Cup quarter-finals between Arsenal and Southampton.
6.48pmArsenal have been hitting the headlines for their unbeaten run in all competitions since the start of the season but it's nights like this where they can really slip up. Arsene Wenger has a tendency to rest a number of his star men for this competition and put his faith in some of the club's academy players, while teams like Southampton see it as an opportunity to not only reach Wembley, but to achieve qualification for Europe next season.
6.52pmIt should be clarified that the likes of Wenger's Arsenal and the other top teams in the Premier League will still see the value of winning this tournament but it certainly doesn't come under the high-priority bracket when manager's set their targets at the start of the campaign. Nevertheless, regardless of the players selected by Wenger and his opposite number Claude Puel, this is a really attractive tie and one which should see players looking to impress their boss and hot prospects seeking a way into the first-team squad on a regular basis.
6.53pmAnyway, without further ado, let's crack on with the team news which is coming from the Emirates Stadium. As expected, Wenger has freshened up his side...
7.00pmAs far as Arsenal are concerned, it's easier for us to tell you who remains in the side than who has been taken out! The only survivor from the team which started the 3-1 victory over Bournemouth is Mohamed Elneny as Wenger makes 10 alterations to his team. Carl Jenkinson comes in at right-back while Jeff Reine-Adelaide features on the right of an attacking-midfield three but the most notable inclusion is Lucas Perez, who makes his return from an ankle injury. Emiliano Martinez is given the nod in goal after penning a new contract earlier this week.
7.05pmSaints boss Puel has named a relatively-strong team. Aside from Harrison Reed and Sam McQueen, each player is experienced and Puel has brought the likes of Shane Long and Sofiane Boufal back into the team after they missed out on the starting lineup at the weekend. The back five looks particularly solid with all of the defence being a first-team regular with Southampton at some point over the last few months.
7.08pmBefore we continue, let me point you in the direction of the match which is currently taking place in the Copa Del Rey between Real Madrid and Cultural Leonesa. The game is going as you'd expect but the minnows have probably had a lot more success than you'd expect. Take a look by clicking here!
7.13pmHEAD TO HEAD! Tonight's match represents the 91st time in which these two teams have met in a competitive fixture, with Arsenal winning 46 times in comparison to just the 19 victories for the Saints. However, while Arsenal have the edge historically, the same cannot be said over the last seven games, with Southampton winning three times and registering two draws during that time. Something not in Southampton's favour, however, is that fact that they have only scored one goal in their last three visits to the Emirates Stadium and that was an own goal.
7.17pmIt wasn't so long ago that the two teams last faced each other in the League Cup. It came in September 2014 - again at the Emirates Stadium - with Southampton overturning an early deficit to progress through to the fourth round. Click here to take a look back at that game, which included a cracking strike from an unlikely source.
7.21pmWe have still got around 25 minutes until kickoff at the Emirates Stadium so you have still got time to take a look at our League Cup section. It's been a busy 48 hours with press conferences and matches so it's best you catch up on everything before we get underway this evening.
7.24pmBoth teams have only been required to come through two matches to reach this stage of the competition. After seeing off Nottingham Forest 4-1 at the City Ground, Arsenal eased past Reading thanks to two goals from Alex Oxlade-Chamberlain.
Southampton have had two home ties against Premier League opposition but they have progressed without conceding a goal. After beating Crystal Palace 2-0, Sofiane Boufal got the only goal of the game as his side beat Sunderland at the end of last month.
7.30pmAs we mentioned earlier, the most notable inclusion for Arsenal this evening is that of Lucas Perez, who has missed the last month of action through injury. Coincidentally, it was a home fixture with Southampton which saw Perez make his debut for the Gunners but he lasted just 62 minutes before being hauled off. Since then, he has featured for another 25 minutes in the top flight with his other appearances coming in this competition and the Champions League. Injuries and the form of Alexis Sanchez and Theo Walcott have derailed his chances to make an impact at his new side so it's opportunities such as the one given to him tonight which he must take. Southampton have one of the best defences in English football so if he can get on the scoresheet tonight, he will definitely be in Wenger's good books.
7.33pmSouthampton are in a similar situation with Boufal. After signing for £21m, he has made just two starts and although he was responsible for his team's win in the last round, he's not done much else. He's only played for 125 minutes all month so he may not be match-sharp but he has to make some kind of impression on Puel and the club's supporters.
7.36pmPREDICTION! While Southampton are probably fielding the stronger side tonight, we cannot ignore Arsenal when they are playing at the Emirates. Even without Sanchez, Ozil and co, they still have Aaron Ramsey to pull the strings and he may be the difference for the North London outfit in a 2-1 win.
7.39pmKicking off 15 minutes later than this match is Manchester United's encounter with West Ham United. It's the second visit to Old Trafford for the Hammers in the space of three days! If you would like to follow that contest as well as this one, click here.
7.43pmThe two teams have made their way out at the Emirates Stadium. We will be underway very shortly. Just hope it's a lot more entertaining than Newcastle's visit to Hull last night...
3 minAfter two minutes of possession, Arsenal give the ball away in the middle of the pitch and it almost leads to Long being set free behind the defence. However, the pace hits the foot of the defender and Arsenal survive.
5 minIt's already clear that Southampton are looking to use the pace of Long. As soon as a midfielder gets the ball, they are looking for the forward to run in behind the defence. It hasn't paid off yet but it's keeping Gabriel and Holding on edge.
8 minAn excellent ball down the right flank almost finds McQueen but he is eased off the ball by Gibbs, who is able to match anyone for pace in English football. Still no chances for either team.
10 minBoufal does well on the opposite flank and it appears that he was brought down by Reine-Adelaide. However, the referee thinks the winger was looking for a free kick and while that was probably the case, it's a definite foul.
13 minI was just about to say that Southampton are beginning to control this game and just as I was typing, they go and take the lead. After a shot was blocked inside the penalty area, the ball fell to Clasie who fired an excellent shot into the top corner from around 16 yards out. Martinez has no chance.
16 minArsenal are still having enough possession to keep Southampton honest but they lack the threat offered by the likes of a Sanchez or Ozil. It's going to have to be a team effort from the Gunners tonight.
19 minIn tonight's other game, Manchester United have already taken the lead through Ibrahimovic. It could be a long night for West Ham United...
22 minWe've not seen any more shots on goal since that strike from Clasie. The Dutchman isn't known for hitting the back of the net but he connected with this shot sweetly and Martinez was left helpless.
25 minSouthampton's two youngsters Reed and McQueen haven't looked out of place. McQueen has plenty of minutes under his belt this season but matches at the Emirates can prove frustrating and so far, it's been anything but. Reed is competing well with the likes of Coquelin and Elneny.
29 minBOOKING! The first booking of the night goes to Elneny, who cynically ensured that Bertrand would make up no more ground down the left.
32 minWe are still awaiting that first shot from Arsenal. This isn't the first time this has happened in recent matches either. It's highlighting how important the likes of Ozil and Sanchez are to the side. Southampton look comfortable.
34 minBOOKING! Yoshida and Rene-Adelaide go to challenge for the ball and the Southampton defender is late, which results in the referee handing out a certain booking.
38 minSouthampton are in dreamland. Not only are Arsenal yet to threaten but they are now 2-0 behind. Boufal took his time on the left-hand side of the penalty area before passing to Bertand and after one touch to control, the left-back fired a low shot into the bottom corner from 14 yards. Big ask for Arsenal now.
43 minSUBSTITUTION! More problems for Wenger who replaces Elneny with Xhaka. I'm assuming that's down to an injury.
45 minIt's still one-way traffic at the Emirates. There's a lot of passes being played in the middle of the pitch but they are coming from Southampton. There are two minutes of added-on time.
8.35pmThe half-time whistle goes at the Emirates Stadium and Southampton go into the break with a two-goal advantage which they thoroughly deserve. Arsenal have offered absolutely nothing and are yet to get a shot on goal. They will be heading out of the competition if things continue like this.
8.48pmThe two teams have started to make their way back out. It doesn't appear that there are any more changes.
47 minSHOT! Well, it's a start. Ramsey runs aggressively towards the penalty area before passing to Perez. The Spaniard has to get his shot away quickly and it lacks power on its way through to Forster.
49 minCHANCE! Arsenal have finally woken up. A ball into the penalty area finds Ramsey and it appears that he only has to tap home past Forster but Reed gets back to pressurise the Welshman and the ball finds the gloves of the goalkeeper.
52 minSHOT! It's extremely ambitious by Long but his strike causes problems for Martinez, with the ball going past the goalkeeper's gloves but trickling wide of the post.
54 minSHOT! That's some strike from 35 yards but Xhaka is never going to beat Forster from there. His shot was heading towards the top corner but the goalkeeper barely had to move to keep it out.
55 minCHANCE! Southampton come within inches of wrapping up this game. It's Van Dijk who caused all of the problems with his run clearing the path for Boufal to head into the penalty area and although his shot seems destined for the bottom corner, it goes marginally wide of the far post.
58 minA head injury to Van Dijk sees this game delayed for the time being but I think he is going to be fine to continue. Like every game he plays, he has been excellent this evening.
61 minSHOT! Coquelin has never scored for Arsenal so he must have been feeling ambitious to score from 25 yards with his weaker foot. His shot hit the target but again, too easy for Forster.
62 minSUBSTITUTION! It's time for Oxlade-Chamberlain, with the midfielder taking the place of Reine-Adelaide. Double-barrelled names all over the place.
64 minSUBSTITUTION! A final change for Arsenal with Maitland-Niles taking the place of Jenkinson.
66 minSUBSTITUTIONS! Two changes for Southampton now with Hojbjerg and Sims coming on for Reed and Boufal.
68 minSHOT! Coquelin is taking every chance to get forward in this second half but he still cannot get a shot on target. On this occasion, he was teed up closer to goal but his strike went two yards wide of the post.
71 minIt's worth remembering that Arsenal have not suffered defeat since the opening game of the season. This may "only" be the League Cup but I'm sure that Wenger is proud of their unbeaten run. They are giving it up without much of a fight.
75 minThere's not a whole lot happening at the moment. Arsenal are trying to get something going but Southampton look too sound defensively to gift anything to their hosts. While Arsenal are lacking a cutting edge, you have to praise Southampton's performance at the back this evening.
78 minCHANCE! While Arsenal need a goal, Southampton have creating the better opportunities now that more space is being left at the back. Long just fired off target after being sent through on goal, while Davis sent an effort just over.
79 minCHANCE! It should be 2-1. Xhaka did well to pick out Oxlade-Chamberlain inside the penalty area but the former Southampton trainee fired over the bar. He can't be missing those kind of openings at this stage in the game.
84 minI think Southampton are going to see out this game without much alarm. Arsenal have fielded a mixed side tonight but this is one of Southampton's stand-out performances of the season.
88 minMcQueen is the next to come close for Southampton but his shot is blocked. Sims has impressed again for the Saints since coming on, just three days after contributing to the win over Everton at the weekend.
90+1 minWe are into added-on time now. This game is done as a contest but Hojbjerg was just denied by Martinez. The Saints are finishing on top.
9.42pmThe full-time whistle goes at the Emirates Stadium and Southampton have comfortably prevailed to reach the last four of the EFL Cup. Goals from Clasie and Bertrand proved the difference as the Saints pushed aside an Arsenal side who had not lost since the opening weekend of the season. They will go into the draw which is coming up in around 20 minutes time.
9.43pmThat will be all from Sports Mole for this game but we hope that you can stick around for the final stages of the Manchester United game. Bastian Schweinsteiger is about to come on for his first appearance of the season! Goodbye for now.