Lineups
Kieran Gibbs returned to the Arsenal first team after a lengthy layoff, meaning that Vermaelen was moved into his usual central role given the absence of Mertesacker, and that Arsenal would select a back four in their true positions for the first time since Guy Fawkes Night. Oxlade-Chamberlain was moved to the bench in favour of Ramsey after the latter’s equalising goal against Sunderland. This meant Rosicky was likely to start on the left to provide a little more protection to the returning Gibbs than Oxlade-Chamberlain was likely to provide.
Milan could reintroduce Zlatan Ibrahimovic, well rested after serving a domestic ban for slapping Napoli’s Aronica. Robinho and Boateng would play around the Swede, with Seedorf the playmaker and Nocerino and van Bommel providing the central strength. Antonini started at left back; the 29 year old tasked with defending against Walcott’s pace.
Match
Arsenal settled quickly into their usual possession game, even away from home, as they looked to impose their own tempo in the opening phases. Milan by contrast were more direct with the ball, looking to turn the Arsenal back four at every available opportunity. The home side won a succession of early corners as they began to ramp up the pressure, albeit without creating anything to trouble Szczensy. Seedorf’s early substitution for Emanuelson also reduced Milan’s potential creativity in midfield.

Arsenal with 65% possession early on, while Milan’s directness was clear to see
On 15 minutes Milan opened the scoring as Nocerino picked up the creativity baton and lifted a delightful ball over the top of the defence for Boateng to chest and half-volley at goal in one movement; the ball flying in off the underside of the bar before Szczesny could react. It was the first real opening of the game, which rapidly settled back into the previous pattern of Arsenal possession and Milan rapid counterattack.
Arsenal’s width was being negated mainly by the relaid strips down each flank of the Giuseppe Meazza, not through any particular unevenness but because these areas seemed heavy and loose underfoot. Players were occasionally slipping on the new turf and the ball wasn’t gliding over the surface as it was more centrally. Arsenal would not usually be labelled as one of the teams utilising width to its maximum in the way that, say, Manchester United do, but Milan are narrower again, and it was certainly the away side more disadvantaged by the relaid pitch.
Milan made it 2-0 with another break, Ibrahimovic incorrectly adjudged to be onside when receiving the ball, and eventually lifting it into Robinho to guide into the far corner.

Vermaelen’s foot on the pitch marking, Ibrahimovic beyond it and offside
Arsenal needed to regroup, but suffered an injury to Koscielny shortly before halftime meaning Djourou’s introduction was necessary. The last time Djourou played in his regular position at centreback, Arsenal conceded eight goals at Old Trafford. As if to remind everybody, he immediately got too tight to Ibrahimovic who turned him with ease, releasing Boateng in behind who selfishly wasted the opportunity by shooting himself when Robinho was waiting for a cutback.
Halftime arrived, and despite having 55% of the first half possession Arsenal had created very little, in fact only a single shot on target. Milan had obviously been more threatening despite registering only two shots on target themselves, with both finding the back of the net. Milan were playing the counterattack to perfection, and also being very adept at preventing Arsenal launching counterattacks of their own with a series of fouls high up the pitch.

Milan’s shots, only two on target but both goals, and fouls high up the pitch to stop Arsenal counterattacks
Arsene Wenger introduced Henry at halftime for Walcott, moving away from the pace mismatch on the wing which had been nullified by the pitch, and reverting to a narrow three behind Henry with Sagna and Gibbs expected to provide the width. Arsenal started on the front foot, but again Milan’s first counterattack looked threatening and a slip by Vermaelen allowed Robinho a free shot at goal, Milan’s third on target and third goal of the night.
Arsenal were lacking in creativity going forward, overcommitting in search of a breakthrough and defensively timid when being challenged with Milan’s direct approach. Wenger reshuffled the back four again with 25 minutes to go, introducing Oxlade-Chamberlain on the right, dropping Song back into the centre of defence, moving Vermaelen to left back and removing Gibbs.
Again Arsenal were allowed the ball as Milan were content to soak up pressure and wait for a chance to counter, and with Ibrahimovic and Robinho now facing Djourou and Song, they would have fancied their chances of a fourth goal. Ambrosini was introduced for Boateng to ensure that an away goal would not be forthcoming. A couple of opportunities fell to van Persie, who worked Abbiati on each occasion but without truly looking like scoring.
There was enough time for Djourou to confirm his inability to play at this level for yet another time, by hauling down Ibrahimovic when he had the Swede in a perfect position to halt his progress. Szczesny’s attempt to dive forward to close the angle on the penalty reduced his lateral reach, when diving directly to his right would possibly have seen him save the resulting spot kick.
Conclusions
Milan sat back, ceded possession, played on the counterattack, exploited Arsenal’s tendency to overcommit, and did it to perfection. Each player knew their role in the system and performed it well. That said, they needed an incorrect onside call, a slip from Vermaelen and characteristic ridiculous defending from Djourou to score three of their four goals.
As the above indicates, Arsenal were the architects of their own downfall. They were positionally indisciplined, made poor mistakes, and gifted their opponents the tie. Away from home in the first leg, 1-0 down to an exceptional goal, the priority must always be to make sure you are still in the tie in the second leg. 57% possession and four shots on target (to Milan’s five) shows that the scoreline was much more emphatic than the balance of play, but a lack of professionalism from Arsenal played into Milan’s hands and took the tie from their own.

Milan with five shots on target to Arsenal’s four