Manchester United, whose defence has looked threadbare since Rio Ferdnand’s suspension, have suffered another setback with the news Mikael Silvestre will miss the next three weeks with ankle ligament damage.

The French defender limped off during Saturday’s 1-1 draw with Leeds after a tackle with Alan Smith.

“It is a big blow for us but we will just have to get on with it,” said United boss Sir Alex Ferguson.

Ferguson is already without Ferdinand and Gary Neville through suspension and Wes Brown is still short of match fitness and has looked uncertain since returning to the starting line up.

Skipper Roy Keane looks set to drop back into a central defensive role in Portugal as United visit Porto in the knock out phase of the Champions League.