Rooney had been in breathtaking form for United, his seven goals in the last seven games netting him the Player of the Month award for October.

His partnership with Carlos Tevez had helped United to 22 goals in six games, and had allowed Ferguson to treat Louis Saha with kid gloves, keeping him in a substitutes role to protect his delicate knee.

Earlier in the day Ferguson had been crowing about having his strongest squad of the season to choose from against Blackburn on Sunday.

Now he will have to have a major rethink about his striking plans for matches ahead against Blackburn in particular, and then Premier League strugglers Bolton, Fulham and Derby.

Ferguson had praised Rooney's form and expressed his belief that Saha was currently at his most effective on the bench.

He said: "Wayne had an injury to begin with and that knocked him back a bit as he missed four or five games.

"We expect players of his ability, young players like him and Ronaldo, to develop and improve themselves.

"They got 23 goals each last year and I think they are capable of getting more than that this year."

On Saha he added: "We are trying to manage the situation he finds himself in terms of his knee condition so we don't play him in every game and the dilemma is do we start him or do we bring him on.

"If you look at the composition of our side now he is different to everyone else so he makes a bigger impact as a substitute.

"At the moment my inclination is to use him as a sub and he is fine with that."

Rooney should be back for United's trip to Liverpool on December 16.