The Gunners breathed life into their Champions League campaign with a 2-0 victory against the Bundesliga champions in October.
Mertesacker expects a strong response from Bayern at the Allianz Arena, and says Arsène Wenger’s side must be at the top of their game.
“They had a Friday night match (against Eintracht Frankfurt) so they are well prepared for midweek – they are clever, the Germans!” the Arsenal vice-captain said.
“We showed that we can beat them, that is a good sign but it will be a different game at their place. They are outstanding in their league, it will be a good game and both teams have a good chance to go through to the knockout stage.
“They will be angry I guess. We are the first team who really challenged them, so they will be on the ball and try to show that they are back and better than us.
“We need to get something out of this game, there is still a bit of pressure and urgency to perform. We need to perform and defend even better.”