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There goes the final whistle! A 2-0 win for Milan against tournament favourites Barcelona. Work to be done by Barca in the second leg in the Nou Camp.
Alves with a cross to the back post, but Abbiati is off his line to claim the ball. Frantic finish to this contest.
Traoré is booked for a late challenge on Mascherano.
There will be five minutes of stoppage time added to this match.
Milan coach Allegri must be thrilled by what he has witnessed here. Not every night do you turn over a side as classy as Barca.
Mascherano enters the action to take over from Puyol for Barcelona.
Traoré replaces El Shaarawy for the home side, who are four minutes and stoppage time away from a famous win.
Puyol rises to meet the cross by his Spain team-mate, but he sends the header well wide of goal. That must go down as a half-chance.
Pedro's run and cross is cut out by Abate and Barca have their own corner here. Xavi to take.
Mario Balotelli seems to be enjoying his night on the sidelines. The Milan fans loving every moment of this one.
Question now focuses on whether or not Barcelona can come up with an away goal. Messi tries to come up with some quality, but Ambrosini halts his run.
Stephan El Shaarawy played provider after a fine dash into the box by Niang. Muntari with an expert finish - his first of the campaign.
GOAL! Muntari thumps a volley into the corner of the net with Valdes well beaten and that will be a 2-0 lead for Milan with Barcelona all over the place at the back.
Xavi gets the ball up and over the Milan. But doesn't come back down in time. Over the bar and another attack falls on deaf ears.
Abate fells Sanchez with a late tackle and that will be a free-kick for Barca 25 yards from goal.
Milan have used the strategy of Chelsea and Celtic to cope with these floods of Barca attacks.
Boateng is the fourth AC Milan player to score two goals against Barça in the Champions League - Albertini, Massaro and Shevchenko.
Iniesta uncorks a shot from distance, but the ball flies a couple of yards wide. Not a bad hit from the Spain midfielder.
A 1-0 win would be a superb result for Milan to take to Barcelona. Plenty of work still to be done.
Pazzini departs to be replaced by Niang for the home team.
Iniesta can't pick out the pass as Ambrosini cuts out the latest Barca attack. Story of the night really.
Milan with everybody back in their own half as Barca come again. Xavi fails to pick out a pass. Shot was surely the best option there, but not taken.
Milan have unsettled Barca this evening with their gameplan. Hunting in packs whenever they are not on the ball.
Abate the latest man needing some treatment for a head knock. Puyol getting his head well and truly bandaged up like the warrior he is.
Pazzini manages to get a shot away. Decent effort, but didn't really have the power to beat Valdes.
Pazzini has rejoined the action, but Puyol still receiving treatment at the side of the park. Milan with a one-man advantage at the moment.
The Milan fans furious that Barca did not give their side the ball back. Unsporting behaviour? Not so sure. But Milan win it back.
Pazzini taking a trip off the park as Puyol lies on the deck at the side of the park. Barca resume in possession.
Puyol and Pazzini collide going for a high ball. Clash of heads and both men are going to require some treatment here.
Iniesta trying to beat three or four men before Abate gets to him with a timely tackle. Milan have worked so hard to defend space.
The Milan fans will take this all night long as Abbiati almost plays himself into a spot of trouble. Does just enough to clear the danger.
Messi decides to go for goal. Some 30 yards out, but he blazes the free-kick well over the bar.
Fabregas takes a tumble under pressure. Wins the foul before being replaced by Sanchez.
Alexis Sanchez set to arrive here for Barca with Milan well and truly on the up all of a sudden. Have certainly picked matters up.
Barca are furious with the Scottish referee Craig Thomson. But this Italian crowd are loving every minute of leading the tournament favourites.
Zapata handled in the build-up to the goal, but Boateng wasn't hanging about there. Pique is booked for protesting. Montolivo with the free-kick.
GOAL! Ball breaks to Boateng on the edge of the Barca box and he thumps the shot low and hard into the corner of the net. Milan lead 1-0.
Alves with a late tackle, this time on El Shaarawy. Free-kick chance 40 yards or so from the Barca goal.
Busquets with a late, sliding challenge on Pazzini. Busquets goes into the book for that one.
AC Milan have only scored one goal in their last four games at the San Siro in the Champions League. They have had 58 shots (incl. blocked) at home in the Champions League this season but only one of them has found the back of the net.
Not sure if you can classify this as parking the bus. Milan can't get on the ball long enough to do anything else. Barca pushing them back almost at will.
Milan having to work so hard to close down space, but offering very little going forward at the moment.
El Shaarawy doing some more stout defensive work to block the cross by Alves.
Boateng guilty of a late, late tackle on Iniesta. Barca in possession in the Milan half. Like they have been for most of this evening.
Xavi trying to cut a dash up the park, but Milan again stockpile the bodies behind the ball. Organised stuff from the home side.
Puyol knocks the ball back to Valdes in the Barca goal. The home fans a bit livelier at the outset of this second period.
Milan get the match off and running for the second period. No changes at the break for either team.
There goes the whistle for the break. 0-0 at half-time. Barca with loads of the ball, but have come up with little in front of goal.
Milan whack another loose ball out of their own box. That should be enough to ensure 0-0 at the break, which will be greeted with more relish by the Milan camp surely.
Don't imagine much time is going to be added to the first period.
El Shaarawy and Puyol chase a ball over the top, but the Barca defender shows his experience to pass back to Valdes, who makes the clearance.
Sloppy play by Mexes as he bundles a pass straight out of play attempting to pick out Boateng.
Barcelona have only lost two of their last 24 Champions League games, both in Britain - at Chelsea and Celtic. Will this be another night of frustration for Barca?
Barca now up to 66 percent of possession, but Milan continue to hold firm with a real sense of purpose.
Messi penalised for a late push on Constant. Messi far from happy about that. Barca feeling the frustration here. Can almost smell it.
All Barca in possession, but little or nothing is happening in front of that Milan goal.
Xavi with the delivery, but a clear push on the back of Zapata by Puyol. That will be a free-kick to the home side.
Mexes slams the ball out of play to gift Barca a corner here.
Valdes happy to collect the ball after a fine cross by Boateng just missed the head of El Shaarawy. Neat stuff by Milan.
Montolivo's free-kick is only headed partially clear before Muntari snuffs out a Barca break.
Muntari doing well to hold up the ball and forces Busquets to bring him down. Milan can take their time here.
The large Milan crowd forced to be patient here whether they like it or not. Messi sees a little one-two fail to come off on the edge of the home box. Barca forced to start again.
Alves tries to find a piece of space behind El Shaarawy, but he is denied by the linesman's flag for offside. Again Milan's tactics pay off.
Montolivo sheds possession needlessly, but Milan again work hard to close down space.
Milan making sure they are hunting in packs whenever Messi is near the ball. Muntari, Constant and Zapata forced to do the covering work there.
So far, so good here really for AC Milan. Barca with loads of the ball, but have yet to cut a dash through this home defence, who are playing with some real grit.
Milan now up to 18 yellow cards for the tournament, more than any other team left in the last 16 of the Champions League.
Iniesta with a little backheel in the home box. Intelligent play, but that man Montolivo is on hand to make the timely clearance.
Barca continue to chip away at this Milan defence and midfield, who are playing with plenty of bodies behind the ball.
Pazzini loses possession and Mexes is the first booking of the night for a late challenge on Messi seconds later.
Barcelona have the highest possession in the Champions League this season with an average of 75.8 percent. Some stat in any tournament.
Montolivo back to make a superb, timely tackle on Messi 25 yards from goal. Barca yet to break down this Milan rearguard.
Some superb range of passing being demonstrated by Montolivo out there. All very even so far.
Stephan El Shaarawy working his way back to help halt another Barca attack. Fine play by him.
Xavi drives a shot at goal from distance, but a comfortable height for Abbiati to make the save.
Valdes plucks a Boateng cross out of the air after Ambrosini was late on Xavi. Poor delivery really.
AC Milan have only won one of their last 10 knockout games in the Champions League, against Arsenal at home in the last 16 last season. Looking brighter so far here.
Boateng nudges the ball wide from inside the Barca box. Much better from Milan, but El Shaarawy may rue that missed chance moments earlier.
El Shaarawy looks to speed in on the Barca goal, but his second touch is far too heavy as Puyol comes across to clear the danger.
Iniesta with a late challenge on Boateng. Barca just overdoing matters in the final third. Needs to be a bit sharper in the home half.
Lionel Messi has scored 56 goals in 74 Champions League games, only Raul has scored more in the competition (71 goals in 142 games).
Busquets with a late, thumping challenge on the lively Montolivo. Milan forced to live off scraps at the moment.
Mexes gets in ahead of Pedro to hook a loose ball past his own goal. Offside flag is late in coming. Almost an own goal.
Milan look to break from a Pique header that is blocked. Muntari takes the wrong option with a through ball as Stephan El Shaarawy is caught offside. Milan forced to play on the counter attack.
The Milan fans quickly on the whistles. Great clearance by Mexes to clear the cross by Alba. Barca already dominating possession.
Boateng thumps a loose ball into the body of Fabregas after he was sent tumbling to the deck. Barca continue to keep the ball with some relish.
Stephan El Shaarawy caught offside after setting off too soon. Just offside. Barca have to keep an eye on him this evening.
Boateng takes out Messi with a late challenge. He can expect a few more of those this evening.
Muntari decides to try a volley from 30 yards, but the ball flies well over the bar. Decent hit, but always rising high. Milan starting strongly enough here.
Not the best of parks, but Barca trying to get the ball on the deck as much as possible. An Iniesta cross is cut out, but Milan fail to take advantage as a quick break comes to nothing.
A crowd of around 75,000 inside the San Siro for this match. Milan looking to get the pace up early on with Barca trying their passing game.
The referee's whistle is blown and we are off and running. Barca get the action started.
Teams in the tunnel, and out they come. Milan in red and black with Barcelona in their changed shirt of yellow and orange. The San Siro is loaded with fans as you would expect on a night like this. A cold February evening, but one that should be ideal for football.
Barcelon are chasing a fourth Champions League success in eight years. As you can imagine, they start as hot favourites this evening. Even away from home. Milan 6/1 Barcelona 8/15 draw 10/3....how many times in a season would Milan be priced 6/1 at home? Might be worth a flutter. Then again, might not.
The big match of the night is in Milan, but the Galatasaray v Schalke match doesn't look too shabby either...click below for LIVE coverage from the other last-16 first leg match.
Our regular blogger Jim White was busy making the case for Bayern Munich glory in this season's Champions League. Would they live with Barca on their day? Do you agree or disagree with Jim? post your thoughts below....
Barcelona are unbeaten in their last seven meetings with AC Milan, winning four and drawing three. This is their fifth encounter in the last two seasons of the Champions League. AC Milan’s last win against Barcelona dates back to October 2004 at the San Siro in the group stages of the Champions League - 1-0.
Jordi Roura (Barca assistant): "This season Milan are different from previous years. To come and play here is a pleasure, in a great stadium and in a fantastic atmosphere. Milan continue to be one of the most prestigious teams in Europe and obviously there is worry about this. It makes no sense to talk about favourites. I don't agree with those who say that Barcelona will definitely win. Milan are one of the most successful teams in Europe and San Siro is always a difficult stadium to play in."
AC Milan coach Massimiliano Allegri: "Over the past two years we have played a few good games against Barcelona. They are the best team in the world and we must try to lay the groundwork for our progress in the tie. We have to limit their time on the ball because in attack they have great players. However, they could concede ground at the back so we need to play with the belief we can go through. Milan will definitely play a good game."
Barcelona are boosted by the return of playmaker Xavi, who has recovered from a hamstring problem to take his place in the starting line-up. Adriano is not in the Barca squad after sustaining a thigh injury, while Eric Abidal and David Villa are both not well enough to have made the trip to Milan. Villa has stayed in Barcelona following two hospital visits caused by a kidney problem last week.
Milan forward Stephan El Shaarawy passes a late fitness test as he looks to shake off a knee injury and will start the match. Fellow striker Mario Balotelli, who joined the club from Manchester City in January, is cup-tied and Nigel de Jong is sidelined with an ankle injury. But there is better news as Giampaolo Pazzini was passed fit after recovering from a hamstring strain to start. Daniele Bonera (thigh) and Robinho (knee) are both out for the home side.
The referee for this evening's match is Craig Thomson of Scotland.
Teams: AC Milan: 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.
Good evening and welcome to LIVE coverage of AC Milan against Barcelona in the first leg of the last 16 of the Champions League at the San Siro. Teams coming right up for you.