Can anyone stop Bayern Munich?That's the question following the German side's 2-0 victory over Arsenal Wednesday in the last-16 of the Champions League.Already 16 points clear in the German Bundesliga and unbeaten in 21 league games, Bayern is looking like the team to beat once again.Bayern, which is hoping to become the first team to successfully defend the title since the competition was revamped in 1992, claimed a hard-fought win thanks to Toni Kroos' second half strike and Thomas Muller's header.It could and indeed should have been different but Arsenal wasted a glorious opportunity in the early stages when Mesut Ozil missed from the penalty spot.The home side's misery was compounded eight minutes before the break when goalkeeper Wojciech Szczesny was sent off after bringing down Arjen Robben in the penalty area.David Alaba stood up to take the spot kick but could only strike his effort against the post.Read: Is Barcelona becoming 'Less of a Club'?Bayern, which won 3-1 at Emirates Stadium at the same stage last season, began to lay siege to the Arsenal goal.And with nine minutes of the second half having elapsed, Kross unleashed a sumptuous strike which flew past substitute goalkeeper Lukasz Fabianski.The visitors refused to let up in their pressure and Robben had an effort well saved when his shot appeared destined for the far corner.Pep Guardiola's side did finally secure the second goal it so badly craved when substitute Muller headed home Philipp Lahm's cross with three minutes of normal time remaining.There was still time for Kroos, who scored in the game between the clubs last season, to hit the post with a measured drive.Arsenal will now head to Munich on March 11 with hopes of pulling off a repeat of their 2-0 victory last season.The same result would give Arsene Wenger's men the opportunity to take the tie into extra-time but it faces an uphill struggle against a rampant Bayern.Read: Barca teaches City a lesson"We started really well and deserved one goal," Arsenal defender Per Mertesacker told Sky Sports."We dropped and dropped after the red card. We kept our defensive spirit."We lost here 3-1 last year against Bayern Munich and went there and beat them and we are looking forward to Munich. Why can't we get back in it?"I think there is no doubt there was contact (for the penalty). I don't know if it was a red card because the ball was a long way from Wojciech Szczesny."Bayern coach Pep Guardiola was pleased with his side's performance but says there is still work to do."Arsenal were much much much better than us for the first 20 minutes. After the red card for their goalkeeper it was another game," he told Sky Sports."When he is the last man then the referee says penalty and red card."It is difficult to play when you see nine players in the box. It is not easy, never. But importantly we controlled this situation and played with patience and at the end found the goal."Last year Bayern had a better result than this evening. It depends on our heads (the second leg)."In the night's other game, Diego Costa's 83rd minute strike gave Atletico Madrid a priceless 1-0 win at AC Milan.Milan, the seven time champion, enjoyed the better of the chances with Kaka's effort tipped onto the crossbar by Atletico goalkeeper Thibaut Courtois.The Belgian goalkeeper also produced a fine save to turn Andrea Pirlo's header onto the post as the home side threatened an opener.But Milan was made to pay for its wasteful nature when Costa stole in at the far post to score a crucial away goal."It was a very difficult match against a great rival but we knew how to soak up the pressure and at the key moment we went after the win," Costa told Spain's Canal Plus."We have a solid advantage and now it's about going back to the Calderon and maintaining it."It's not over yet but we know it's a good result tonight."We have confidence in ourselves. Some people have been doubting us recently but we have no doubts. We are a team and we are very strong."(CNN)ANN.Az