The Manchester derby is going to be a game that will come with a big shocker, I believe Manchester United will come out stronger in that encounter, a win in the champions league will make them play with all they've got just to be the top dog of this derby.
Manchester United were not brilliant in the CL, they only narrowly managed to win that game, BTW, it is the Manchester Derby, and current form sometimes doesn't matter in such games, it is about bragging rights for the fans, and players more often than not give all their best. It would be a very tight game and so difficult to predict.
Having said that, i think City would just manage to get the win, they are the better team and i think they have far more better players than Manchester United, City's attack might just be too much for United to handle, with Doku, Foden, Silva and Haaland most likely to start, they'll definitely outscore Manchester United.