An early goal from Toni Kroos put Arsenal under pressure, and although the Gunners responded well, they defended a bit like they just had their wisdom teeth removed, and Bayern take a massive advantage to Germany for the second leg.
In a match which Arsenal started brightly and had some good attacking spells, Bayern's quality and Arsenal's...interesting...defending told in the end, and Bayern emerged from the Emirates with a 3-1 victory that means Arsenal have to basically find a create-life-from-inanimate-tissue-type miracle to advance to the next round in the UEFA Champions League.
Arsenal actually started fairly brightly, with Theo Walcott looking to get behind Munich's defense. But seven minutes in, the makeshift nature of Arsenal's back four, coupled with some shoddy tracking and marking from others, saw Bayern get a crucial away goal. Franck Ribery managed to work the ball out wide on the right to Thomas Muller; Lukas Podolski failed entirely to get back and prevent an overlap on that side while Thomas Vermaelen went walkabout into the middle. Mikel Arteta moved out wide, but didn't prevent the cross back in to Toni Kroos, whose movement had eluded the attention of a ball-watching Aaron Ramsey. When Kroos hit a hard shot off the turf from 20 yards, Per Mertesacker was the only thing near him. Per is thin, and couldn't stop the shot.
It was a bit of a slop show.
Arsenal set about trying to make amends, but Munich were now feeling the flow. Philip Lahm was making a nuisance of himself on the right flank, and he won the corner 21 minutes in from which more problems ensued. Daniel van Buyten was completely free and unmarked coming across the front of the pack for the short corner, and his header was low and hard on goal. Wojciech Szczesny could only parry the ball directly in front of him (perhaps he could have done a bit more), and Thomas Muller's eyes got big as he stuck out a leg and crushed the ball into the roof of the net from a yard out. It was pretty much easy stuff. 2-0 up after 21 minutes, Munich were looking to put the tie to bed before it was a quarter over.
But Arsenal were prepared to keep on going, and they did. Jack Wilshere put a good free kick in in the 35th minute that eventually came to Mertesacker, but his attempt couldn't find the back of the net, and Bayern escaped. Arsenal kept up the pressure, keeping the ball for good stretches of time, but their defense was always looking a bit shaky, and Mario Mandzukic was unlucky not to find the net just before halftime, his header going just wide. The only consolation that Arsenal could take from the first half was the yellow card for Bastian Schweinsteiger, which means he will miss the second leg of the tie in Munich. Svein Oddvar Moen's Norwegian whistle gave the Gunners some respite shortly thereafter, and they would need to find something soon after the break or risk fading into oblivion much like General Zod in the Phantom Zone at the end of Superman II.
Luckily for Arsenal, Manuel Neuer decided to go full Fabianski on us all. Jack Wilshere swung a good corner in on the 55th minute, and Neuer proceeded to do something like this:
Neuer: [translated from German] KEEPER--GUYS--MINE--I GOT IT--wait. Is that...what...was I supposed to buy wheat bread or white from the store tonight? [Ball sailing over his head]. I'd better back up and have a re-think about this grocery list. Bread, wheat, I think, cheese, peanut butter, chicken...rice...wait, rice? or potatoes [ball bounces in front of Podolski, Podolski heads ball]. Apples, pie crust...wait...I should back up, or maybe to the side, I have to concentrate on...wait. DANG IT. I'M A FOOTBALL GOALKEEPER IN A FOOTBALL MATCH. [Ball drifts into net].
At any rate, it was 2-1, and Arsenal had found a spark of some kind. Manuel Neuer is a great keeper most of the time, but it was a puzzlingly derpy derp, derpily derped.
Arsenal would keep coming forward. Olivier Giroud and Tomas Rosicky entered the fray, and immediately set about doing their things, which is, namely, Giroud getting on the end of a Walcott cross only to shoot it hard against Neuer's legs from 15 yards, and Rosicky running around being generally good at playing midfield in soccer. But four minutes and a good Szczesny save later, Arsenal's Vicodin Defense would show up again, and Bayern would find a third.
Mandzukic did good work holding up the ball from a long punt forward, and passed back to Arjen Robben. At this point, Thomas Vermaelen did a silly thing, and ran right up to Robben, who ghosted past the now-turned Belgian. Vermaelen tried to recover as Santi Cazorla failed to track the run of Philipp Lahm, who received the touch pass from Robben and cracked a low cross across the face of goal where a mess of Bacary Sagna and Mandzukic looped the ball up and over a retreating Szczesny and in.
Mario Gomez nearly made it four shortly thereafter, but his effort from a Luiz Gustavo rebound went harmlessly over the bar. Arsenal looked worn out and Munich were only too happy to see their lead out after three minutes of stoppage. There were noticeable boos in the crowd after the final whistle. Wilshere gamely said the tie is not over yet after the match, but it's a hard row to hoe for Arsenal at the Allianz in three weeks' time.