Last Updated: 20/02/13 9:39pm
The referee blows his whistle for full-time. AC Milan have beaten Barcelona 2-0 and take a clear lead for the second leg. That will be a match well worth watching.
Traore wastes a chance to create a chance for AC Milan as his run forward is halted by Pique. Niang was in space.
AC Milan, as they have done all night, defend superbly in numbers. Barcelona just haven't been able to provide Abbiati with any major worries.
Boateng takes control of the ball for AC Milan and plays the hosts out of a trouble. The midfielder has been the best player on the pitch tonight.
AC Milan have been fantastic in this half. They lead 2-0 and that is setting us up for a really, really interesting second leg.
We now have both former Portsmouth players on target for the hosts tonight. Play up AC Milan the home crowd sing!
GOAL MUNTARI! Great play between Niang and El Shaarawy sets up Muntari and the midfielder beats Valdes with a driven volley. That is a really superb goal for AC Milan to move 2-0 up.
Xavi sends the free-kick just over the bar. No real danger for Abbiati as he happily watched the ball through.
Great work from El Shaarawy down the left to win a corner for AC Milan. He has produced a very lively display.
AC Milan continue to pose a few questions for the Barcelona defence as a cross from the right is scrambled clear.
Barcelona haven't reacted too well since falling behind. AC Milan continue to defend in numbers and continue to do it very well.
Xavi wastes a chance to get a shot in on goal from the edge of the AC Milan box. He tries to play a neat pass but the ball is cleared.
We have another break in play as Abate and Puyol receive treatment. This game has been stop-start over the last 10 minutes.
Pazzini falls in an aerial tangle with Puyol. Both players need some treatment and the home side have a free-kick.
Abate produces a fantastic challenge to win the ball from Iniesta on the left flank. AC Milan have been really, really good in defence so far.
Messi fires a free-kick high, high, high over the AC Milan goal. Not the greatest moment in his fantastic career.
More danger for Barcelona as AC Milan nearly knock the ball through to Boateng on the edge of the six-yard box, The situation is stopped but this isn't a great time for the away side.
Pazzini continues to produce a really clever game as he wins a free-kick on the halfway line. The forward was fouled by Puyol as he kept possession.
That should really give this game some spark. Barcelona have been dominating possession but without looking dangerous. They will have to do a bit better now.
GOAL BOATENG! AC Milan take the lead! Boateng fires home from just inside the Barcelona box after a scramble from a free-kick. A great finish and it really is now game on.
Busquets hurts himself as he tackles Pazzini. It was late from the Barcelona midfielder and he is correctly booked. He doesn't like it but referee Craig Thomson from Scotland continues to get it right.
More of the same as AC Milan frustrate Barcelona by defending in numbers. Still plenty of interest though as the minutes tick by.
Barcelona enjoy a long spell of possession. AC Milan continue to defend really well in numbers as the away side are forced to take it slow.
Barcelona are now 4/5 to win this match with Sky Bet, AC Milan are 5/1 and the draw is 13/8 You can get price boosts for AC Milan to win 1-0 at 9/1, Barcelona to win 2-1 at 12/1, El Shaarawy to score next at 12/1 and Iniesta to score next at 14/1.
The first half ends with very little additional time. No goals yet but plenty of action as AC Milan defend very well. Barcelona look dangerous so plenty to look forward to after the break.
Pique plays a loose pass out of play for a throw as Barcelona appear to show a little bit of frustration. Half-time arrives soon to put that right.
Another Barcelona move ends with the ball going through to Abbiati in the AC Milan goal. The great defending continues for the hosts but can they keep it going all game?
Another break in play now as Montolivo receives treatment. He is also fine to continue and the action goes on.
Messi concedes a free-kick as he pushes Constant to the ground. AC Milan continue to defend very well.
We have a break in play as Muntari receives treatment. He is fine to continue and joins the action again.
El Shaarawy can't quite reach a cross from the left. Valdes gathers and Barcelona play it out again.
Muntari does well to win a free-kick as he is crowded out by Sergio Busquets and Pedro. A good chance for AC Milan to break up the game.
Barcelona are finding it tough to break down AC Milan. They are having all of the possession but so far there have been no major worries for Abbiati.
Dani Alves is caught offside as he tries to make space in the AC Milan box. It was a good ball from Xavi to find him.
Good work from Massimo Ambrosini to win the ball from Messi just inside the AC Milan half. Barcelona's star man is heavily involved at the moment.
Messi is causing all kinds of problems for Constant when he moves to the right. You could easily say he is a constant threat but that would be a bit too simple.
All Barcelona in terms of possession currently. We have seen it plenty of times before but AC Milan are defending well and in numbers.
Barcelona are enjoying a spell of pressure. Pedro has a weak shot at goal and Abbiati easily deals with it.
Messi falls under a diving challenge from Mexes just inside the AC Milan half and the defender is rightly the first player to be booked.
Fabregas concedes a free-kick on the edge of the Barcelona box as he dives in a bit late on Boateng, who continues to be all over the place for Milan.
Barcelona enjoy a spell of possession at the back. AC Milan have been good at defending in numbers so far so it's hard for the away side to find space.
Xavi has a go from distance but Abbiati is equal to the threat and gathers with ease in the centre of his goal.
Boateng has been at the centre of all AC Milan's play so far. He is one of two former Portsmouth men starting for the hosts tonight with Muntari also playing.
Boateng goes close from the corner as he sends a sharp effort just wide of the Barcelona goal. Plenty of action so far.
El Shaarawy looks to have space to run through one-on-one with Valdes but he overhits the ball and allows Puyol to clear behind.
A remarkable slice from Muntari on the halfway line ends with the ball caught by Abbiati like a fielder on the boundary in cricket. It certainly wasn't a backpass.
It's been a good start to this match. Plenty of swagger from Barcelona as always but AC Milan are looking dangerous as well.
Barcelona cause a little bit of panic as a cross from the right is deflected behind close to his goal by Mexes. No corner though as the flag is raised by the linesman for offside.
AC Milan break at speed but Stephan El Shaarawy runs clear a little too quickly and is caught offside.
Barcelona wins a quick couple of corners. The second flag-kick results in AC Milan knocking the ball clear after an attempted shot from Gerard Pique.
Cesc Fabrehas takes a tumble to win a free-kick on the halfway line. Barcelona keep possession and AC Milan get men behind the ball.
The TV cameras show Mario Balotelli smiling on the sidelines. He isn't part of the AC Milan side tonight after playing for Manchester City in the Champions League earlier in the season.
AC Milan enjoy a spell of possession with Riccardo Montolivo running out of space as he tangles with Jordi Alba. Goal-kick to Barcelona.
Nearly time for us to get started. AC Milan in red and black with Barcelona wearing their interesting orange and yellow away shirt.
Steve from Bath writes: 'The last time these two met in the CL at the San Siro it was goalless. That won't happen tonight. In what should be a cracker I think the Italian side can beat the odds and force a draw......a score draw.....I'll go 1-1.....and a small saver on the 2-2!'
There are five changes in the AC Milan side for this clash after the victory over Parma on Friday night. Mario Balotelli is cup-tied after playing for Manchester City in the Champions League earlier in the season so his spot is taken by Stephan El Shaarawy. Andres Iniesta, Xavi and Carles Puyol all start for Barcelona after missing the weekend's win at Granada.
Here are the teams for tonight - AC Milan: Abbiati, Abate, Mexes, Zapata, Constant, Ambrosini, Montolivo, Muntari, Boateng, Pazzini, El Shaarawy Subs: Amelia, De Sciglio, Traore, Niang, Bojan, Cristante, Yepes
Barcelona: Valdes, Dani Alves, Pique, Puyol, Jordi Alba, Xavi, Busquets, Fabregas, Pedro, Messi, Iniesta Subs: Pinto, Sanchez, Thiago, Mascherano, Montoya, Song, Tello
Jamie Casey of Sky Bet provides us with a betting update ahead of the match: 'Hosts Milan were initially 6/1 to beat Barcelona but have been cut down to 5/1 after considerable backing. However, the tournament favourites remain 1/2 on, with Lionel Messi 23/10 to score the opening goal of the game.' You can also get price boosts for Kevin-Prince Boateng to score at 14/1, AC Milan to win 2-1 at 20/1 and Barcelona to win 3-0 at 10/1.