MANCHESTER, England (Reuters) -- Manchester United defender Rio Ferdinand has returned to training but will not face West Ham United this weekend, manager Alex Ferguson said on Friday.

The centre back has been struggling to shake off a calf injury and has not played since picking up the problem in the warm-up before the Premier League leaders' 2-1 defeat by Wolverhampton Wanderers on Feb. 5.

United's pursuit of a record 19th English league title, as part of a potential treble of the FA Cup and Champions League, has been hit by a string of injuries to defenders in particular.

Rafael has also started training but will not be available for Saturday's trip to struggling West Ham, while fellow defenders Wes Brown and John O'Shea are expected to return to training on Monday and Jonny Evans is suspended.

"It still leaves us considerably short for tomorrow in terms of the right-back position, we'll have to solve that," Ferguson told a news conference.

"I thought the two-week break (for internationals) would bring a few of them on, and it has, but not enough to play tomorrow."

Ferdinand was delighted to be close to a return, writing on Twitter: "Buzzing to be out on the training pitch again."

Anderson will travel with the team to West Ham but fellow midfielder Darren Fletcher is grappling with a bad virus and will be assessed next week when United travel to London again to face Chelsea in their Champions League quarter-final first leg.

United are seeking to repeat their 1999 treble but their injury situation is hampering their chances.

"It's great to be involved in three competitions," said Ferguson. "The difference in '99 was that no one was injured. That was the benefit we had then, the advantage.

"These next couple of weeks are crucial for us to get all these players back. If we get them back then it definitely enhances our chances, there is no question about that."

United top the table with 63 points, five ahead of Arsenal who have a game in hand. They could go eight points clear, for a few hours at least, if they beat West Ham as the Gunners play later in the day.

SI Apps
We've Got Apps Too
Get expert analysis, unrivaled access, and the award-winning storytelling only SI can provide - from Peter King, Tom Verducci, Lee Jenkins, Seth Davis, and more - delivered straight to you, along with up-to-the-minute news and live scores.