You can find out how the match unfolded with our minute-by-minute commentary below.
4.18pmAfternoon all. So, the match that Millwall and Wigan Athletic supporters have been waiting for is almost upon us. One of these teams will be in final of the FA Cup come 7.15pm this evening - unless we have extra time and penalties of course. With such a big prize on offer for these two underdogs, it promises to be a great encounter.
4.19pmBefore we get into all the pre-match chat, statistics etc - the teams news from Wembley is beginning to filter through. Who has made the cut? Let's start with Millwall...
4.21pmMILLWALL XI: Forde; Dunne, Shittu, Beevers, Lowry; Abdou, J Smith, St Ledger; Henry, Keogh, C Taylor
4.23pmThe big news for Millwall is that Andy Keogh has been given a lone striking role ahead of Jermaine Easter and Rob Hulse. However, Liam Trotter's recent knee injury means that he has only been deemed fit enough for a place among the substitutes. Sean St Ledger and James Henry are also included.
4.28pmSomewhat surprisingly Ali Al-Habsi has been recalled to keep goal for Wigan in place of young Spaniard Joel Robles. Al-Habsi has not featured since the beginning of March. Elsewhere, Callum McManaman will start on the wing, while James McCarthy will operate in a holding midfield role.
4.32pmA quick weather update and surprise, surprise - it's raining. Quite heavily in fact. That will probably please Wigan manager Roberto Martinez though because it should liven up the pitch, which will allow them to play their slick passing football. Millwall on the other hand may have benefited from a drier playing surface.
4.36pmTalking of "slick passing football" - Wigan showed that in abundance during the quarter-finals of this competition. They scored three times in the space of four first-half minutes to secure a 3-0 win away at Everton. It was the sort of performance that made you wonder how they are in the Premier League's relegation zone. They also saw off Bournemouth, Macclesfield, Huddersfield earlier in the tournament.
4.38pmMillwall, though, should not be daunted by what is ahead of them. In the fourth round they knocked out Premier League outfit Aston Villa at The Den. Preston, Luton Town and Blackburn Rovers are the other teams that have fallen to the Lions.
4.43pmAs mentioned in the introduction to the commentary, the winner of this encounter will not just reach the final of the FA Cup. They are also 99% certain to qualify for the Europa League next season, providing that Chelsea and Manchester City seal their own route into Europe via the Premier League. With both of those sides in the top four, it looks extremely likely.
4.47pmThe history books would have you believe that it will be Wigan that reach the showpiece event and the Europa League. They've not lost any of the last four meetings between these two teams, winning three and drawing one. During that time Millwall have failed to score as well.
4.51pmWhat's more, they've only scored in just one of their previous eight encounters with Wigan. That was a 3-1 victory back in January 2001. Goals have actually been in short supply for Millwall since the turn of the year when leading goalscorer Chris Wood joined Leicester City.
4.56pmPutting all the previous results to one side, you have to fear for Millwall today when taking into consideration the size of the pitch at Wembley. It's a wide playing surface, which will suit Wigan down to the ground. They are bound to have more of the possession, which means that the Millwall players have got a lot of running ahead of them. That's what could prove to be the distance when the final whistle is blown.
5.01pmOne thing Millwall will certainly win today is the number of supporters inside the ground. Each side were given 31,000 tickets, which the Lions sold with ease. However, Wigan were only able to part with around 21,000 of their allocation. That has resulted in the Football Association making a 'Neutral Zone' for the first time at an FA Cup semi-final. Of course there wouldn't be a problem if this was played somewhere like Villa Park - where it should have been! That's a rant for another day though!
5.06pmStaying with the supporters, there is a really good atmosphere building inside Wembley. The Millwall fans as you would expect are making the majority of the noise.
5.11pmRight then, here come the players. Incidentally, Millwall will be in their home colours of blue this evening, while Wigan are wearing an unfamiliar red strip. There's a warm embrace between the two managers, who know each other well. Kenny Jackett coached Martinez when he was a player at Swansea City.
1 minGAME ON! Here we go then. Millwall, kicking from left to right, get this FA Cup semi-final started.
3 minIt's been a brisk start by Wigan, who have had the first opportunity of the tie. The Millwall defence seemingly parted for Jordi Gomez, but as he shot from the edge of the area, Mark Beevers threw himself in the way to block the effort. Millwall cannot allow to give the Spaniard that much space too often.
7 minTo be fair to Millwall, they've settled well and if anything are the more dominant of the two teams. James Henry has swung a couple of dangerous free kicks into the penalty area, but the Wigan defence have dealt with the threat. The aerial route will probably be Millwall's best chance of scoring today.
11 minHenry really is Millwall's key player today. Just now he started a move when he lofted a pass through to Chris Taylor and then got himself into a position where he could shoot once Taylor had returned the favour. His shot may have skidded wide, but he is looking extremely lively for the Lions.
13 minA worrying moment for Millwall as goalkeeper David Forde was down following a collision with Wigan striker Arouna Kone. It seems as though he took a knock to jaw. The Irish international is up now but looks a little groggy. From a Wigan point of view, it may be worth testing him with a couple of lofted crosses into the area.
15 minSAVE! Well, Forde shows that he is still extremely alert with a smart save to deny McManaman. It's a swerving effort from the winger, but the Millwall stopper has enough time to get behind the ball and parry clear the danger. That's the first piece of action for either keeper.
20 minThe match has now settled into a rhythm that many people expected. Wigan are seeing virtually all of the ball and look neat and tidy. However, goalscoring chances are few and far between because at the moment the Millwall rearguard are looking extremely disciplined.
27 minMillwall may have been tight defensively in the opening 23 minutes, but as soon as they switch off, they are punished. It's a lovely goal from a Wigan point of view as Kone picks out Shaun Maloney inside the area with a neat pass. The Scottish international's finish is instant, which leaves Forde in the Millwall goal no chance. Advantage Wigan.
29 min"1-0 to the empty seats" sing the Wigan fans. As far as football chants go, that's rather amusing! As for Millwall, they need their supporters to get behind them now.
34 minMaloney, Gomez and Kone are beginning to run this match for Wigan. Their passing is crisp and more often than not finds its intended target. This is where Millwall are going to have dig in and wait for their opportunity.
39 minStill nothing to report in the way of goalscoring opportunities. In truth, it has the feel of a training match. Wigan are the attack, while Millwall scuttle around searching desperately for a chance to have some possession.
43 minSAVE! At last a shot! Unsurprisingly it is Wigan who have the attempt as Kone collects possession on the edge of the area and cuts the ball back for Gomez, who curls the ball goalwards. Forde is quick to react though and is able to push clear the danger.
45 minThere will be one minute of stoppage time at Wembley...
6.07pmWell, that went pretty much how it was expected. Millwall did well for 10 minutes or so, but after that Wigan took control and got the goal their domination deserved. They've been the dominant force ever since, but haven't created too much more.
6.09pmFrom a Millwall point of view, I've got to confess that I expected maybe a little bit more. Yes, Wigan were always going to have more of the ball, but the Lions have not been great without possession. They've not harried Wigan and forced mistakes. Instead, it's been easy for Martinez's team to keep hold of the ball.
6.13pmThat is surely one thing that Jackett will be demanding of his players during the second half - make Wigan work hard to keep hold of the ball. As good as the likes of Maloney, Kone and Gomez are - they are only human and will make errors if they are rushed.
6.16pmFormer Wigan winger Kevin Kilbane, who is working for BBC Sport this evening, believes that Liam Trotter could hold the key for Millwall:
"If Liam Trotter comes on for Millwall he will provide support for Andy Keogh, who has been very isolated up top," he said.
45 minHere we go then, the second half is underway. A big 45 minutes ahead for both of these clubs.
49 minA quick tweet from Stan Collymore, who is commentating on this match for talkSPORT: "Dear FA,I'm at Wembley,please have the SF'S at club grounds again. Atmos is awful,and not befitting a SF. Cheers. Stan."
52 minCHANCE! That is the best and worst of McManaman in the space of five seconds. The winger shows great skill to put two Millwall defenders on the seat of their pants, but when he should have crossed for Kone, he opted to shoot from an impossible angle instead. Predictably, the ball flies well over the target.
57 minVery little has changed from the first half, as Wigan continue to pass the ball around the pitch with ease. This really looks like a pre-season friendly and unless tactical changes are made by Jackett, it will remain that way.
59 minCHANCE! A sight of goal for Millwall as Taylor is fouled 25 yards from goal by Emmerson Boyce. The free kick duties are given to Henry, who curls the ball over the wall. It's always rising though and Al-Habsi watches the ball sail over his crossbar.
61 minSUBSTITUTION: The first switch of the evening comes from Wigan, who take off the ineffective Jean Beausejour. He is replaced by James McArthur, which may see Maloney move into a wider role as Wigan switch to a slightly more defensive 4-5-1.
65 minCHANCE! This is better from Millwall, who are now at least making a fight of things. They force a corner which is swung over by Henry. Big Danny Shittu rises above everyone inside the box, but his timing is slightly off and he heads the ball well over the crossbar. The crowd respond as well. We have a semi-final at last!
68 minSUBSTITUTION: And now there is an attacking switch from the Lions. Smith in the midfield is replaced by striker Rob Hulse, who will play alongside the so far isolated Andy Keogh. It may have taken some time, but Millwall are now forcing the issue a little bit.
71 minWe now have a game on our hands folks. Millwall have opened up and are pushing for an equaliser. Wigan look a little shocked if truth be told, but at the same time they now have some spaces to exploit in the Millwall half. A boring tie as turned into a watchable one!
73 minSUBSTITUTION: Here comes the creative Trotter for Millwall - they really are making their intentions known. The former Ipswich Town midfielder has replaced the more defensive-minded Nadjim Abdou.
75 minCHANCE! Now Wigan have woken up! Both teams are spoiling us! It's Gomez who has his third attempt of the match and he's bound to be disappointed not to have troubled the scorers. On this occasion he tries his luck from a narrow angle, but he can only find the side netting.
80 minIt may have been against the run of play, but Wigan won't care one jot - they are heading for the final of the FA Cup. Gomez threads a neat pass through for McManaman, who shows great composure to round Forde before rolling the ball into an empty net. He now has goals in the FA Cup against Huddersfield, Everton and Millwall in the FA Cup this season. He's a talent, that's for sure.
85 minAs if things weren't bad enough for Millwall, off the pitch their supporters are fighting among themselves and with the police. There really is no need for something like that. Very, very poor.
89 minVideo footage of the clashes in the stands show young children crying. It's still not stopped either - plenty of pushing and shoving going on. There really is no place for that. A large number are picking on one police officer. It may ruin it for the vast majority, but Millwall should be banned from next year's competition. Simple as that. It happens too often.
90 minWe will have three minutes of stoppage time here at Wembley...
7.08pmWigan are through to the final of the FA Cup and they deserve it - both on and off the pitch. They were much the better side and played some really good stuff. They will now watch tomorrow's other semi-final between Chelsea and Manchester City with great interest.
7.09pmAs for Millwall, some of their supporters don't deserve an FA Cup final for their actions. They were fighting for a good 30 minutes - both against each other and the police. Very, very poor and let's hope that the authorities dish out the correct punishment.
7.10pmThat's all we have time for from Wembley. Thanks for joining us this evening and until next time, goodbye.