Rio Ferdinand could miss Manchester United's clash with Liverpool at Old Trafford on Sunday.

The England defender has missed the Premier League leaders' last two fixtures, with Gerard Pique standing in at the heart of the United backline alongside Nemanja Vidic for the 2-0 defeat of Bolton on Wednesday night.

Manager Sir Alex Ferguson said: "Rio Ferdinand is doubtful for Sunday with a back problem.

"I had to find out about Gerard Pique. We've got great confidence in the lad and he's come through very well.

"They are all top players so you have to put your faith and trust in them."

Serb centre-back Vidic sustained a bloody nose in the win over Bolton - as United moved three points clear at the top of the table - but is expected to be fit to face Liverpool.

Sporting Life / Eurosport