Nemanja Vidic has admitted it will take at least two months before he is back to his best.
He certainly made his presence felt too, guiding United's defence to only their fourth clean sheet in the Premier League this season, which ensured they head into 2013 seven points clear of Manchester City.
However, Vidic is refusing to accept his comeback is complete.
After virtually 16 months on the sidelines, including rupturing his cruciate during the devastating defeat to Basle last December, the 31-year-old knows there is plenty of work ahead.
"The doctor is managing the games I am playing at the moment," he told MUTV.
"Over the first two or three months I have to really look at that because sometimes I might have a reaction.
"This is a process I have to go through.
"I am glad I have managed to play after three months. It is nice to be on the pitch and playing games.
"Hopefully I can play more often so I can build my form and play better."