Manchester United midfielder Darren Fletcher has been sidelined for six weeks because of a knee ligament injury.

Fletcher suffered the setback in Scotland's 1-1 draw against Croatia in midweek in a friendly at Hampden Park.

Manager Sir Alex Ferguson said: "It is a bad blow for us as Darren will be out for six weeks."

Louis Saha is also ruled out of the match against Aston Villa because of a hamstring problem.

Nani is doubtful because of thigh problem while Gary Neville and Mikael Silvestre remain sidelined through injury.

Aston Villa defender Olof Mellberg is poised to return to the side at Old Trafford.

The Swedish international, who is bound for Juventus in the summer, was suspended for the shock home reversal by Sunderland after his red card at Portsmouth but is set to replace Craig Gardner.

Martin O'Neill has to decide whether to keep faith with on-loan Liverpool goalkeeper Scott Carson who has looked short of confidence in recent games and made crucial errors.

Villa will be looking to end a run of four games without a win but have not beaten the Red Devils in the Barclays Premier League for 12 years.