Manchester United defender Mikael Silvestre will be out for three weeks with ankle ligament trouble, manager Alex Ferguson said on Monday.

The France defender was hurt in a challenge with Leeds striker Alan Smith during the 1-1 draw at Old Trafford on Saturday.

"Mikael will be out for three weeks, which is a blow for us at this stage of the season," Ferguson told the Manchester Evening News. "But we have just got to get on with it."

The English champions, who travel to Porto in the Champions League second round on Wednesday, are already without defender Rio Ferdinand due to suspension.

With 12 games to go in the English Premier league, Manchester United trail leaders Arsenal by seven points and Ferguson's defensive problems are mounting, with Gary Neville also due to start a four-match ban shortly.