By Rob Kelly at Allianz Arena
We are facing a mammoth task to turn around our Champions League last-16 tie against Bayern Munich after conceding four times in a disappointing second half in Bavaria.
After Arjen Robben curled in the opening goal in the 10th minute, it was clear we were facing a big challenge - but we responded well and drew level when Alexis converted after his penalty had been saved.
But Laurent Koscielny’s injury at the start of the second half seemed to disrupt us, and we conceded twice in the space of six minutes.
Robert Lewandowski headed beyond David Ospina to put the hosts back in front, before Thiago Alcantara swept home the third moments later.
The Spanish midfielder added a fourth with a deflected strike from the edge of the area to leave Arsene Wenger’s side in real trouble, before Thomas Muller completed the scoring right at the end.
It capped off a miserable night for the Gunners, who are now facing a sixth successive exit at the last-16 stage.
SETTING THE SCENE
With an almost full complement of players to choose from, Wenger had some big decisions to make with his team selection - with the headline news Granit Xhaka’s return to the starting line-up.
The Swiss international had missed the last four domestic games through suspension, but was drafted in to add some muscle and guile to the midfield, where he partnered Francis Coquelin.
The other notable change saw Alex Oxlade-Chamberlain shifted out of the central midfield role in which has thrived of late to start on the right flank, with Theo Walcott dropping to the bench.
David Ospina continued in his role as our Champions League goalkeeper after impressing during the group stage, with Petr Cech on the bench in Bavaria.
Bayern, meanwhile, were without Franck Ribery and Jerome Boateng, but fielded a star-studded team containing the likes of Lewandowski, Douglas Costa and Robben.
It would not be easy against a Bayern side that had won their last 15 Champions League matches at Allianz Arena but, having faced the Germans six times in the past four seasons, at least we knew the size of the task facing us.
Facing a side that average more than 60 per cent possession in every game, it was no surprise that we were forced on to the back foot early on.
The hosts were starting to purr and with 11 minutes on the clock, our task grew even greater as Robben cut in from the right to curl a trademark strike into the top corner.
It was just the sort of start we had hoped to avoid, and it could have got even worse soon afterwards but for a well-timed tackle from Laurent Koscielny to deny Lewandowski.
Bayern were dominating possession, leaving us to chase the ball for long periods and try to spring attacks on the counter.
We sprang into life for one such attack in the 26th minute as Alexis broke forward, only to be shoved over by Mats Hummels right on the edge of the area. Mesut Ozil took the resulting free kick, which Manuel Neuer spilled in the area but no one was on hand to poke home the loose ball.
But moments later we were back on level terms after Koscielny was tripped in the area after a quickly-taken corner. Alexis stepped up to take the penalty, only to see Neuer save it - but the Chilean reacted quickest to fire in the rebound.
It was just the boost we needed after a trying opening 25 minutes, and the 4,000 or so travelling Arsenal fans packed into one corner of the Allianz exploded in delight.
Bayern responded as you would expect them to, and the next chance was theirs as Arturo Vidal hooked Thiago’s ball back at the far post and Lewandowski headed over from close range.
We had visibly grown in confidence after the equaliser and back we came, with Oxlade-Chamberlain finding space in the area to pick out Xhaka, but his powerful drive was well held by Neuer.
Lewandowski would head another effort over the bar before the break, while Ozil forced Neuer into action for the final noteworthy chance of a fascinating opening 45 minutes.
The sight of Koscielny limping off within minutes of the restart was not the ideal way to begin the second half, and matters soon got worse as Bayern retook the lead.
It came as Lahm burst down the right flank and delivered an inch-perfect cross to Lewandowski, who hung in the air before directing his header back across goal and into the far corner.
Things were going downhill fast, and that feeling only deepened as Lewandowski flicked the ball through for Thiago minutes later, with the Spaniard making no mistake to extend the hosts’ lead.
Bayern were in full flow now, forcing the Gunners’ defence into a series of errors and Lewandowski nearly bagged his second when he rounded the onrushing Ospina, before curling an effort on to the crossbar from a tight angle.
The Colombian goalkeeper was then called into action moments later to make a good save, but he could do nothing when, from the resulting corner, Thiago blasted in from the edge of the area.
The game had rapidly careered out of Arsenal’s control and it leaves them chasing a tie that already looked a huge ask to turn around.
Substitute Thomas Muller added a fifth after pouncing on another defensive error right at the end, to cap off a miserable night in Bavaria for Wenger’s men.
Referee: Milorad Mazic
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