London - Manchester United manager Sir Alex Ferguson revealed on Friday that defender Rio Ferdinand could be out for as long as four weeks with a thigh problem.

He suffered the injury in training last week, and has missed both of United's Premier League games so far.

"Rio is going to be out for three to four weeks," said Ferguson, meaning he will miss United's matches against Wigan Athletic and Arsenal, and England's internationals against Slovenia and Croatia.

Serbian centre-back Nemanja Vidic, though, is fit and should play against Wigan.

"Nemanja has trained with us for 10 days and he is ready for the game," said Ferguson. "Hopefully he will be okay by tomorrow." (dpa)