The England hitman was carried out of training on Tuesday as the storm over his future raged.
And Sir Alex Ferguson has confirmed Rooney will now be out of action until the middle of next month.
"Wayne will be out for three weeks," he told radio station Key103.
The news only adds another twist to the events of the last few days. It was Rooney's claim that he was not suffering from an ankle problem - which completely contradicted the words of his manager - following England's draw with Montenegro 10 days ago that started the whole rumpus in the first place.
Rooney has already sat out matches against Valencia and Sunderland prior to the international break.
He did make a brief appearance against West Brom on Saturday, when he was shunted out on the left wing, but is now set to miss the remainder of a congested period of the season.
Significantly, the timescale would see him ruled out of the first Manchester derby of the season on November 10.
In addition, Rooney will also miss the Champions League return against Bursaspor a week earlier, next week's Carling Cup tie with Wolves, plus Premier League games against Stoke on Sunday, Tottenham and Wolves again when they visit Old Trafford on November 6.