I don't think they would go out on the field with a very weak team. Although the next game is more important, Leipzig is not an easy team either.
They can start the match with a good team and then make changes to rest the players, without allowing injuries and without making the high tempo match. There's still time for the game, we'll see
I'm more convinced that Bayern Munich will use half of their key players against RB Leipzig. It's not just the first match of the Champions League that is very important, the match against RB Leipzig is also important to secure their position.
Maybe a player like Lewandowski will not play, because he is a very reliable player in Bayern Munich attack against Barcelona later.
I agree with you. Winning a Champions League match is more important than winning against Leipzig. Lewandowski may not play against Leipzig. Because he is the main player of Bayern Munich. If he performs against Leipzig and is injured, it is an irreparable loss for Bayern Munich. However, I hope Bayern Munich's performance against Leipzig will not be bad, even with fewer key players.