It could have been one of the great European nights, one of the most memorable of all comebacks, one for Arsène Wenger to look back fondly on in retirement on the Cote d'Azur with a glass of cognac in his hand. Instead it ended in frustration and acrimony with Wenger embroiled in a post-match confrontation with the referee in the tunnel which could lead to another touchline ban for the Arsenal manager.
Wenger's anger and disappointment was assuaged by pride at the way his players tackled a vertiginous four-goal deficit against the leaders of Serie A. Rolling forward in a red tide which all but swept Milan away, Arsenal were within a goal of levelling the scores before half-time. But the next goal proved elusive thus Milan's fourth in the 79th-minute of the first leg, a Zlatan Ibrahmovic penalty which seemed a footnote at the time, a twisting of the stilleto, was decisive.
"I'm disappointed, but very proud," said Wenger. "We have given everything. If you do that you have to accept the result even if it is a disappointing one. We had the chances to qualify, we were very close. The players put in a faultless performance with a fantastic spirit, but we pay the price for a bad first game,
He was also furious, at Slovenian official Damir Skomina, primarily for the number of free-kicks he was persuaded to give in Milan's favour in the second period which broke up the game and prevented Arsenal building momentum. "I'm not happy with the referee," Wenger said. "Every free-kick was for them. They sensed it quickly on the pitch and used it very well."
Wenger waited for the referee at the final whistle and, when prevented form speaking to him, followed the officialdown the tunnel where he is reported to have sworn at him. If the referee reports him to Uefa they are likely to punish Wenger with another touchline ban. Wenger received one for his comments about the dismissal of Robin van Persie when Arsenal went out at this stage at Barcelona last season and began this year's campaign banished from the touchline.
When he calms down Wenger will reflect there was a lot to encourage him and Arsenal fans. Alex Oxlade-Chamberlain gave a mature performance in midfield, Tomas Rosicky and Theo Walcott continued their recent good form, the defence, until the game became stretched, were much improved. But ultimately this defeat means another year without a trophy, another year of potential unrealised, another summer of speculation about their star player.
That man scored, as usual, a coolly taken 43rd-minute penalty, but ironically it was Van Persie who missed the critical chance, though it was less a miss than a superb save by Christian Abbiati. Laurent Koscielny, after six minutes, and Rosicky after 25, scored the other goals.
Milan fielded eight of the team which eviscerated Arsenal in San Siro but, admitted coach Massimiliano Allegri, took a risk by including two European rookies, teenage striker Stephan El Shaarawy and left-back Djamel Mesbah, and playing three forwards. This prevented Arsenal's full-backs pushing on but it meant the visitors struggled to contain Arsenal in midfield where Oxlade-Chamberlain was excellent until fatigue caught up with him.
Wenger had insisted the the gap between the teams could be bridged but to judge from the atmosphere at kick-off few fans seemed to believe him. The opening two goals changed all that and suddenly this arena felt like a stadium at last. Arsenal were given a useful bonus as early as the fourth minute when Mark van Bommel, that arch-niggler, was cautioned for bringing down Rosicky. The yellow card may have momentarily disturbed Van Bommel's equilibrium because two minutes later he let Koscielny escape to head in an Oxlade-Chamberlain corner.
The second goal came from another unforced error. Thiago Silva, intercepting a harmless Walcott cross, unaccountably passed it straight to Rosicky on the edge of the box. The Czech slid his shot neatly inside the post. The Emirates erupted. Now they believed. The deficit could have been halved even earlier with Van Persie, on his weaker right foot, shooting tamely after Walcott had released him, then bringing a diving save from Abbiati with his left .
Arsenal maintained the pressure, driving forward relentlessly. Pressing high up the pitch they pushed Milan back, forcing mistakes. A few minutes before the break Oxlade-Chamberlain broke down the right and drove into the box before being tripped by Mesbah. Despite a delay Van Persie tucked away the penalty as if in his back garden.
The interval helped Milan regain their poise and the tie was approaching the hour before Arsenal seriously threatened again. Rosicky fed Gervinho whose shot seemed sure to go in when it deflected off Philippe Mexes, but Abbiati made a superb save with his leg, then recovered to claw away Van Persie's follow-up. "The one you would want the chance to go to is Van Persie, but you have to give credit to the goalkeeper," said Wenger.
Five minutes later it could have all been over as Wojciech Szczesny played a risky pass to Alex Song which Ibrahimovic intercepted. The keeper, stranded, could only watch gratefully as the Swede's snapshot rolled just wide. The error reflected the fact that Arsenal were tiring with Oxlade-Chamberlain, then Walcott, both forced off with injury.
Milan now looked the more dangerous and should have killed the tie when Antonio Nocerino hit Szczesny's leg when presented with a near open goal. It mattered not, Arsenal's legs were heavy, their minds weary, their sting drawn.
Man of the match Rosicky.
Match rating 8/10.
Referee D Skomina (Sloven).