Manchester United boss Sir Alex Ferguson could be without Wayne Rooney, Phil Jones, Rio Ferdinand and Nani for Saturday's FA Cup fourth-round tie at Anfield.

APWayne Rooney could be a big miss

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Rooney, Jones and Nani picked up ankle knocks during Sunday's Premier League victory away to Arsenal, while Ferdinand expected to play in that match but was ruled out with a recurrence of a back problem.

Reports on Friday suggest that Rooney has been unable to take part in training all week - although his problem is not expected to rule him out of action in the long-term - while some have suggested that Nani could be missing for around two months.

United have struggled with injuries all season: Ashley Young and Tom Cleverley are both thought to be at least a week away from returning, Anderson is sidelined for a fortnight and Darren Fletcher and Nemanja Vidic are out for the season.