With Marouane Fellaini missing from training on ahead of the Bayern game, who could come into replace the Belgian?
The Belgian had started the first leg against Bayern Munich, and manager David Moyes will face a dilemma as to who to replace him with.
Michael Carrick and Ryan Giggs also started the fixture as the Scotsman packed the midfield, so assuming the duo also feature again from the very beginning, who could come into take Fellaini's place?
Here's a look at the candidates...
The Englishman has been playing at centre-back frequently of late, and stood up well to Franck Ribery at right-back in the first leg. But with Ferdinand and Vidic available, and Smalling fit to cover for Rafael, United can afford to dispatch the versatile Jones to perform a holding job in midfield. He has had mixed performances in this role this season, starting there six times, but his defensive mindset may be just what the Red Devils need to allow their more creative players to flourish. A solid option.
The only United player who has been criticised more than Fellaini this season, Tom Cleverley may have a chance to redeem himself in the most unlikely of circumstances. Up against the man who could hamper his future United career in Toni Kroos, Cleverley will have all the motivation he needs to make a point. He has not featured since being withdrawn with injury in the Manchester derby, but was an unused substitute against Newcastle at thr weekend.
One player who did feature in midfield against Newcastle is experience midfielder Darren Fletcher. In the midst of a comeback season from illness, the Scotsman is yet to show he is back to his best form defensively, but achieved an impressive 96 per cent pass accuracy at the weekend. His previous Champions League experience could be vital in terms of keeping the team composed early on, but is he up to playing 90 minutes twice within a week?