Arsene Wenger has told Arsenal to "make the impossible possible" at Bayern Munich with the Gunners needing to score at least three times in Wednesday's Champions League last 16, second leg clash.

Having lost the first leg 3-1 at Emirates Stadium three weeks ago, Wenger's side face an uphill task to become only the second team to win at Bayern's Allianz Arena this season.

Wenger is urging his squad to be positive with Bayern weakened by the loss of France wing Franck Ribery with a sprained ankle, while both Germany midfielder Bastian Schweinsteiger and defender Jerome Boateng are suspended.

"We're chasing the game in a very difficult environment against a team that has no doubts at all," Wenger told Arsenal.com.

"We have to try to put them on the back foot.

"Subconsciously anyway, they think they are through and we have to subconsciously think that we can do it.

"But our mentality is to go there, not resigned, but ambitious and provoke things.

"We have to go there and give ourselves a chance to qualify with everybody believing we can do it.

"The chance is small, but that chance makes the impossible possible. That would be a great credit for our team to do it. We have to try to achieve it."

Arsenal's task is especially daunting against a buoyant Bayern side who proved their mettle by twice coming from behind in Saturday's 3-2 win at home to Fortuna Duesseldorf which left them 20 points clear in the Bundesliga.

Bayern have lost just once at home this season when Bayer Leverkusen pulled off a shock 2-1 win last October in the league, but Munich have won all of their eight games so far in 2013.

Even without their stars Ribery, Schweinsteiger and Boateng, coach Jupp Heynckes has a strong squad to choose from but right-wing Thomas Mueller has said the team will not take the Gunners lightly.

"Arsenal have nothing to lose, they can focus on attack," Mueller, who has scored 17 goals in 32 games this season, told the Bayern website.

Bayern know all about European disappointment having lost last season's Champions League final at home to Chelsea on penalties and are wary of resting on their laurels, despite the big win in London.

"We had a 1-0 win in Milan and then lost 3-2 at home to get knocked out," said Mueller remembering Inter Milan's 3-2 win in Munich in 2011 which saw Bayern exit at the same stage in the competition.

"We can't afford to be too relaxed."