After Arsenal's mauling in Milan everyone has written off the north Londoner's chances of progression.
Arsene Wenger's team must start strongly at home and with Alex Oxlade-Chamberlain likely to come into the midfield they pose a different kind of threat than when Mikel Arteta is playing. Milan have said they know little about the England under-21 international, so expect to see the Arsenal teenager on the ball a lot.
No team has ever progressed in the Champions League after such a heavy first-leg defeat. If Arsenal score they must hope Milan grow nervous, wary of being embarressed.
Here are some key battles that could decide the outcome of this encounter.