The veteran playmaker's last appearance came as a substitute in the 4-1 FA Cup win against Fulham last month but Sir Alex Ferguson is confident the 38-year-old will be back in a red shirt soon.
"Paul has had a little knee injury which we sent him to a specialist for," revealed the boss. "It is a little bit floating in the knee which he has had for many years.
"He will be back, though. It won't be too long. We are just managing it at the moment."
As for Wayne Rooney's fitness, Sir Alex admits that the England striker may not be ready for Saturday's Barclays Premier League encounter at QPR.
"I wouldn't think so," he conceded. "He came in for the first time yesterday [Wednesday].
"The medical people are dealing with him. He just had a bad sinus infection. He got it on Saturday morning and didn't turn in. He has been on medicine but came in yesterday. Hopefully he will start training on Thursday."