The Scot, while ruling Rooney out of the Sunderland encounter with the ankle injury he aggravated at Bolton last Sunday, revealed he could be available to Fabio Capello who is due to name his squad for the game on Monday.
Related ArticlesGiggs: Rooney will benefit from intense scrutinyFerdinand plots easy comebackSunderland v Man United: match previewBruce predicts Wayne Rooney selectionHernandez savours winnerCapello hopeful on Rooney"Wayne trained yesterday and he wants to play tomorrow," Ferguson told local radio station Key103.
"But I have to take the view that this injury has been niggling away for a while and he kept on playing.
"I have to be dead sure that I am doing the right thing because Wayne has not been doing himself justice.
"I think in a week he will be fine. Obviously we don't play in a week, so it is up to Fabio Capello whether he wants him to."
On this occasion it clearly works to England's advantage that they only have one match to play in the forthcoming international break, on the second of the two dates.
"The Montenegro match is another 10 days away," confirmed Ferguson.
"By that time I would expect Wayne to be 100 per cent."