Per Mertesacker has admitted that Bayern Munich are the toughest opponents that Arsenal could have drawn in the last 16 of the Champions League.
The Gunners welcome the defending European champions to the Emirates Stadium on Wednesday for the first leg of their knockout tie.
"Bayern were very strong last year, they achieved everything, they got the treble and were very sharp and almost the perfect team," he told the club's official website.
"But with [Pep] Guardiola in charge, they look even sharper. They look to get even more possession, which is nearly impossible but he has put something in, that Barca style.
"I think they have improved this season on what they are doing so it will be a really tough one and demands a lot from our side - mainly defensively."
Arsenal reached the last 16 of the competition by finishing in second place in Group F.
