The Red Devils face a date with the German champions at Old Trafford on Tuesday night.
Only a win is enough for United, and even then a draw in the other group game is required for them to progress to the knockout stages.
Asked about beating Bayern, manager Erik ten Hag stated: "There were stages in the game where we played very good [4-3 loss away earlier this season].
"It was end-to-end for a long time in that game but also we suffered some mistakes that were absolutely avoidable.
"One thing for sure against Bayern Munich you have to play your best because they have a very good team and very good individual players.
"But as I say, Chelsea also amazing players, we dominate them and I think we can do it against Bayern as well.
"It's our team, we are not consistent, clear. But we have also a very good performance and highs, so if we get it and are in the right spirit then we are able to do it and we are able to beat any opponent.
"As I said, the game against Chelsea, the game against Everton, even the game against Galatasaray. I know this team can perform really high levels. We didn't do it three months ago, we did it last week.
"I know we can do it, when we have the right mood, the right spirit, it starts with the right attitude, everyone is ready for it, we are able to do it."