Ramsey slots home second from Ozil through ball
Mkhitaryan's first goal for Arsenal with shot across keeper
Return leg takes place in London on 15 March
AC Milan 0-2 Arsenal
Milan midfielder Franck Kessie makes a huge error - which almost lets Arsenal in. Near the halfway line he just launches the ball towards his goal inexplicably.
Danny Welbeck gets a shot in but Gianluigi Donnarumma - inches away from him - saves it, with the ball hitting off the striker and going wide.
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Arsenal has played well, with a swagger. But Welbeck still cannot find a goal and the defense is not as effective as it should be. Not fully convinced yet.
Gbade
Peter Williams: If Arsenal can do this to Milan, imagine what Brighton could do.
Watford to beat Arsenal on Saturday. Normal service will be resumed.
Kevin, Hornchurch
AC Milan 0-2 Arsenal
Arsenal's Granit Xhaka and Milan midfielder Franck Kessie have a falling out. The referee has words with both but no cards shown. Xhaka always seems to be on the brink of a booking.
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Alexander Schimmel: I just knew Wenger's master plan to become so bad that we are the underdogs going into every match would pay off eventually.
I still love Arsene, even if sometimes it feels like I'm the only one. Yes, we are all familiar with the shortcomings but we've still won three more trophies than our much lauded North London neighbours. Come on you Reds!
Julian J, Epsom
Why are people surprised? Arsenal can beat anyone on their day, no change there. This doesn't cover up our leadership vacuum, defensive frailties and psychological weakness all of which are down to the manager.
John, Luton
AC Milan 0-2 Arsenal
We are under way in the second half. What's going to happen in the next 45?
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Rezaa Sait: It pains me to say this but wouldn't Europa League success mean another few seasons for Wenger? Isn't that what every Arsenal supporter is against?
Am I the only Arsenal fan who thinks we're a goalkeeper, centre back and quick, strong central defensive midfielder from being an excellent team? If we can get to Europa final and qualify for Champions League it's not so bad.
Ben, London
We all know Arsenal can win by two goals in Milan and lose by three goals at the Emirates. Let's not get our hopes high. It's still Wenger's reign.
Lex
Image source, Getty ImagesAC Milan 0-2 Arsenal
For the first time since April 2011 (for Real Madrid against Spurs), Mesut Ozil has managed two assists in a European game.
He has now been directly involved in 100 goals for Arsenal (37 goals and 63 assists).
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This is the Arsenal I know and love... give Wenger another two years please.... come on you Gunners...
Andi, Harrogate
'The Italian job' - starring Mkhitaryan anyone?
Matt, Winchester
Any one else bet on Arsenal to lose tonight? The one time I bet on Arsenal to lose and they are killing AC Milan! What is going on at Arsenal!
Toby Briggs, Cambridge
AC Milan 0-2 Arsenal
Alistair Bruce-Ball
BBC Radio 5 live at San Siro
I can't quite believe what I've seen there and Arsene Wenger practically skipped down the tunnel in delight on the half-time whistle.
Milan actually have been quite disappointing but Arsenal have punished them and they should really be 3-0 up with Henrikh Mkhitaryan's shot clipping the bar which was a little bit wasteful.
It was a wonderful Ozil through-ball for Arsenal's second goal though and Aaron Ramsey took it with such composure, just waltzing round Gianluigi Donnarumma to stick it into an empty net.
A remarkable first-half in the San Siro and classic Arsenal under Wenger, just when you think they're down and out they remind you exactly what they can do. The inconsistency, as ever, must be maddening for Arsenal fans.
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Craig Smith: Welcome back Arsenal, where have you been for three months?
Grumpy Expat: Well after that first half performance I think it's clear Wenger hasn't lost the dressing room just yet!
Classic Arsenal football being played tonight. Don’t know what people are whinging about.
Ben
AC Milan 0-2 Arsenal
Alistair Bruce-Ball
BBC Radio 5 live at San Siro
The second goal is a thing of beauty. Who would have believed this?
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Antoine Allen: Even if Arsenal win tonight. It only paints over the rising damp at the Emirates. The team and management's needs a refurbishment.
Waqas Khan: Arsenal fans need to stop moaning and support the team during the match at least. Leave the criticism towards Wenger and the team till at least after the match.
Nokeeroe: This game looked tough on paper but Arsenal are crushing the so called Italian giants.
You can't win these ties in the first legs, but you can lose them, or so they say.
Just the one other goal at half-time across the remaining three games.
Atletico Madrid 1-0 Lokomotiv Moscow
Borussia Dortmund 0-0 Red Bull Salzburg
CSKA Moscow 0-0 Lyon
AC Milan 0-2 Arsenal
We didn't really see that first half coming.
Aaron Ramsey
Arsenal are in control.
Mesut Ozil plays an excellent through ball to Aaron Ramsey, whose quick feet leaves keeper Gianluigi Donnarumma on the ground - and he can tap into an empty net.
Good goal.
Image source, ReutersAC Milan 0-1 Arsenal
Milan winger Suso, once of Liverpool, fires an effort over from outside the box. We're into the final minute of stoppage time.
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Jay Barnes: Mkhitaryan might have forgotten how to cross, pass, dribble or play football in general but he clearly hasn't forgotten how to score in Europa League.
As much as I love Arsenal, and hold Wenger in the highest regard, we truly are going backwards. It's plain for all to see, and given our ownership/board issues I don't see a way out of the decline. A new manager will bring new ideas but he would still be constrained by our business model. In regards to tonight, I can't imagine us going a whole 90 minutes against any team and not conceding. We may need more goals.
Anon
Lewis:I thought Mkhitaryan was number seven. Any clue why he’s wearing number 77?
Because Alexis Sanchez wore it for Arsenal earlier this campaign. Weird Europa League rules don't let two players wear same shirt number for a club in a season
AC Milan 0-1 Arsenal
Almost 2-0 to Arsenal. Danny Welbeck - after a superb run from midfield - plays a pass across the box to Henrikh Mkhitaryan, who - like he did for his goal - cuts onto his right foot. This time though his effort clips off the crossbar. Should have done better really.
AC Milan 0-1 Arsenal
Hakan Calhanoglu and Suso stand over the free-kick. After what feels like an age, Suso takes it - and slams it right into the wall.
AC Milan 0-1 Arsenal
Free-kick to Milan as Aaron Ramsey brings down Suso.