The Gunners host the German champs on Wednesday and will seal their passage if they win.
Robin van Persie hit two goals to see off Norwich 2-1 in the Premier League on Saturday and Walcott set up one of them. He said: "We are playing beautiful football at this moment in time.
"Robin up front makes our jobs so much easier. He's one of the best strikers in the world right now.
"We can keep on winning."