United skipper Nemanja Vidic is likely to be sidelined until the festive period.
Sir Alex Ferguson has revealed to MUTV that he does not expect his commanding centre-back to return to action until late December, although Shinji Kagawa should only be missing for another month or so.
After recovering from a cruciate ligament injury sustained in last year's Champions League exit at Basel, the Serbian suffered another knee problem that required surgery.
"With Kagawa, it's easy to assess that one whereas with Vidic it's a bit more difficult," the boss told MUTV. "Maybe around Christmas time.
"I think Kagawa should be available in four weeks' time but Vidic I think we're talking about December, maybe around Christmas time."