Match ends, Milan 0, Arsenal 2.
AC Milan 0-2 Arsenal (agg 0-2)
Arsenal put their recent problems to one side as a polished performance at fallen giants AC Milan gave them the upper hand in their Europa League last-16 tie.
The Gunners arrived at the San Siro at arguably the lowest point of manager Arsene Wenger's 22-year reign, yet responded to a run of four straight defeats with a confident and controlled display against their Italian hosts.
Henrikh Mkhitaryan's first goal for the club put the Premier League side ahead, cutting in from the left to fire in with the aid of a deflection off Milan skipper Leonardo Bonucci.
Wenger spoke before the game about his team showing fight without compromising their attacking principles - and they delivered in a dominant first-half performance.
Aaron Ramsey deservedly doubled their lead before half-time, collecting Mesut Ozil's piercing pass through the centre of Milan's defence to round keeper Gianluigi Donnarumma and tap in.
Milan tried to up the tempo after the break, wasting a clear early chance to pull one back when Giacomo Bonaventura spooned over the bar.
But Arsenal were largely unruffled from then on, limiting the home side to half chances with a solid defensive effort.
The two away goals now make the Gunners firm favourites to reach the quarter-finals after next Thursday's second leg at Emirates Stadium.
"Overall it is important to win, but it is not qualification. We have to finish the job at home. I am happy with the spirit and response we gave," said Wenger.
"We were not in a position to take risks, but we could not be too cautious as you lose fluidity. We defended with resilience until the end."
Awesome Arsenal forget recent struggles
Arsenal travelled to Italy looking for respite from a torrid recent run during which the north London club have lost four straight games for the first time since October 2002.
A toxic atmosphere has been hanging over the club as fans continue to turn against Wenger, with 88% of the Arsenal Supporters' Trust's (AST) 1,000 members voting this week in favour of the 68-year-old Frenchman's contract being terminated at the end of the season.
Few of the 2,000 or so Gunners fans who travelled to the San Siro would have been confident of seeing a positive performance.
But they watched a display containing commitment and organisation - two qualities sorely lacking in recent weeks - against a Milan side revitalised under Gennaro Gattuso.
Arsenal striker Danny Welbeck led the line superbly with his tireless running, allowing Ozil, Mkhitaryan and Ramsey to find space from deeper positions when the team attacked.
And defensively, they worked hard as a unit - marshalled by skipper Laurent Koscielny - to deny Milan space in attacking areas.
Arsenal's problems are not going to be masked by one good result.
However, their display could not help but give the impression that, even in their lowest moments, it would be foolish to write off their chances of somehow going on to win the Europa League and secure a route back into the Champions League.
Gattuso's Milan fail to live up to expectations
Seven-time European champions Milan are a shadow of the force they once were, languishing in seventh place in Serie A despite spending more than £200m last summer in a bid to change their fortunes.
However, they went into Arsenal's visit on a crest of a wave following the arrival of former midfielder Gattuso.
He has transformed their season since replacing the sacked Vincenzo Montella in November, leading them on a 13-match unbeaten run and giving them faint hope of climbing into Serie A's European qualification places.
Therefore, there was optimism among the 70,000 Rossoneri fans inside the atmospheric San Siro that Gattuso's side could make a huge statement in front of a bigger European audience.
It seemed justified as they pinned Arsenal back in the opening few minutes - but that was as difficult as it got for the Gunners.
Arsenal quickly wrestled their way back into the game, their passing and movement causing uncertainty in the Milan defence and their solidity seeing the home attack quickly run out of ideas.
"We made too many mistakes," said Gattuso. "We never played as a compact team and they deserved the win.
"Every time they attacked, they could have scored. Playing at this level is something new for our lads but there were too many mistakes.
"In football, you never say never. We'll go to London to try and win, we're not going on an excursion."
Man of the match - Henrikh Mkhitaryan (Arsenal)
While Koscielny, Ramsey and Ozil all had strong cases to be named man of the match, Mkhitaryan shaded it after producing one of his best performances in an Arsenal shirt.
The Armenia international has showed few flashes of brilliance since arriving from Manchester United in January, but demonstrated his quality in a competition where he has thrived since moving to England.
While Mkhitaryan struggled to make an impact in the Premier League for United last season, he scored six goals - including one in the final - as the Old Trafford club won the Europa League.
In the San Siro, he had already been giving young Milan right-back Davide Calabria a torrid time before putting Arsenal on the path to victory with his first goal for the Gunners.
He should have scored a second, clipping the crossbar shortly before Ramsey doubled the lead.
Nevertheless, Mkhitaryan's performance offered encouragement to the travelling fans who will want to see him produce similar displays on a more regular basis.
Ozil celebrates Arsenal century - stat attack
- Arsenal earned their first win in the opening leg of a last-16 European tie since February 2011 (2-1 v Barcelona in the Champions League).
- The Gunners are the first side to beat AC Milan at the San Siro in the Europa League/Uefa Cup since February 2002. The Italians had gone 10 games without losing between these defeats.
- Arsenal's victory ended a run of 13 games without defeat for AC Milan, with their previous loss before this coming back in December against Atalanta in Serie A.
- Ozil has been directly involved in 100 goals in 189 appearances for Arsenal - 37 goals and 63 assists.
- With five goals and nine assists this season, Ozil has had a hand in more goals than any other Arsenal player.
- Arsenal's opener ended a run of 599 minutes without conceding a goal for AC Milan.
Back to the Premier League for sixth-placed Arsenal. The Gunners, who are 13 points adrift of fourth-placed Tottenham, host mid-table Watford at the Emirates on Sunday (13:30 GMT).
- 2CalabriaSubstituted forBoriniat 79'minutes
- 8Fernández Saez
- 63CutroneSubstituted forAndré Silvaat 69'minutes
- 10CalhanogluSubstituted forN Kalinicat 62'minutes
- 7N Kalinic
- 9André Silva
- 21ChambersSubstituted forElnenyat 85'minutes
- 31KolasinacBooked at 60minsSubstituted forMaitland-Nilesat 62'minutes
- 8RamseyBooked at 71mins
- 11ÖzilSubstituted forHoldingat 80'minutes
- Clément Turpin
- Shots on Target
Second Half ends, Milan 0, Arsenal 2.
Foul by Suso (Milan).
Jack Wilshere (Arsenal) wins a free kick in the defensive half.
Attempt missed. Danny Welbeck (Arsenal) right footed shot from outside the box misses to the right. Assisted by Granit Xhaka.
Attempt missed. Granit Xhaka (Arsenal) left footed shot from outside the box is high and wide to the left. Assisted by Henrikh Mkhitaryan.
Foul by Mohamed Elneny (Arsenal).
Giacomo Bonaventura (Milan) wins a free kick on the left wing.
Foul by André Silva (Milan).
Laurent Koscielny (Arsenal) wins a free kick in the defensive half.
Delay over. They are ready to continue.
Substitution, Arsenal. Mohamed Elneny replaces Calum Chambers because of an injury.
Delay in match Calum Chambers (Arsenal) because of an injury.
Foul by Giacomo Bonaventura (Milan).
Henrikh Mkhitaryan (Arsenal) wins a free kick in the defensive half.
Foul by Fabio Borini (Milan).
Ainsley Maitland-Niles (Arsenal) wins a free kick in the defensive half.
Attempt missed. Alessio Romagnoli (Milan) header from the centre of the box misses to the right. Assisted by Giacomo Bonaventura with a cross following a corner.
Corner, Milan. Conceded by Rob Holding.
Attempt blocked. Giacomo Bonaventura (Milan) right footed shot from the left side of the box is blocked.
Substitution, Arsenal. Rob Holding replaces Mesut Özil.
Corner, Milan. Conceded by Laurent Koscielny.
Attempt blocked. Franck Kessié (Milan) right footed shot from the right side of the box is blocked. Assisted by Fabio Borini.
Substitution, Milan. Fabio Borini replaces Davide Calabria.
Attempt missed. Suso (Milan) left footed shot from the right side of the box misses to the left.
Davide Calabria (Milan) wins a free kick in the defensive half.
Foul by Danny Welbeck (Arsenal).
Attempt blocked. Giacomo Bonaventura (Milan) right footed shot from outside the box is blocked.
Aaron Ramsey (Arsenal) is shown the yellow card for a bad foul.
Foul by Aaron Ramsey (Arsenal).
Lucas Biglia (Milan) wins a free kick in the attacking half.
Substitution, Milan. André Silva replaces Patrick Cutrone.
Attempt missed. Ricardo Rodríguez (Milan) left footed shot from outside the box misses to the right following a corner.
Corner, Milan. Conceded by Ainsley Maitland-Niles.
Offside, Arsenal. Aaron Ramsey tries a through ball, but Danny Welbeck is caught offside.
Foul by Granit Xhaka (Arsenal).
Franck Kessié (Milan) wins a free kick in the defensive half.
Shkodran Mustafi (Arsenal) wins a free kick in the defensive half.
Foul by Nikola Kalinic (Milan).
Foul by Danny Welbeck (Arsenal).