Sir Alex has revealed Nemanja Vidic could make a surprise return in Wednesday's Champions League tie against CFR Cluj.
The United captain has been sidelined after a knee operation and was tipped to make his comeback around the festive period. However, the manager feels the Serbian may be ready for midweek after starting training again with the main group.
"For the last year and a half, I think he's only played around 10 or 12 games [note: it's 13 since October 2011]," the boss stated. "The best way forward for us is to listen to Vida himself. He has the experience to know what's best for him and know when the time is right to come back into the team.
"He started training in the week and he did okay. He hasn't been involved in the real competitive part but at least he's back training with the first team. It would be nice to play him on Wednesday [v Cluj]. I wouldn't be adverse to playing him on Wednesday. I think he’s done all his work but he needs matches.
"Good defenders win you the league. I gave Rio a rest on Wednesday with tomorrow's game in mind. Chris Smalling and Phil Jones being back gives the right problem that I need."