Bayern have no problems in the Bundesliga and, on the contrary, they lack strong opponents to train with, so I expect Bayern to play at full strength and therefore most likely to beat United. Moreover, the game could end with a score of 3-5 or something like that (if United is able to resist), but I think that Bayern will win. The most interesting thing is who will win in the Copenhagen - Galatasaray pair. Both teams played solid football and it's a pity that someone had to be the loser.
I've often said this actually, that they are already comfortable when passing the 4th match, they just need to relax and wait for their next opponent in the Champions League. But will they be able to accept being defeated by Manchester United? in my opinion not, because prestige is also at stake there. They also looked not very ambitious in the previous match and could only play a draw and I think that's what they will do, if they don't win then at least they don't lose, that's the most realistic in my opinion.
Last year, Bayern qualified after the 4th round, but this did not stop them from beating Barcelona away with a score of 3-0, and then Inter at home with a score of 2-0. Bayern is not a team that will give points to anyone even if the game has no tournament significance. In addition, Müller said after the game with Copenhagen that he was angry that they could not win. It is logical to assume that now some of this anger and dissatisfaction will go on United