Rooney is desperate to play in his first World Cup

But his club have insisted that the 20-year-old, who broke a metatarsal in his right foot in April, will only be fit after the group stage is over.

United added that at that point a "very careful assessment" would be needed to decide if Rooney could participate.

He rejoined the squad in Germany on Wednesday after a scan in Manchester.

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And the BBC's chief football correspondent Mike Ingham, who was in the reception of the team's hotel when Baden-Baden when the striker returned, heard Rooney declare 'The Big Man is back in town'.

Rooney had flown to Manchester on Wednesday for the scan in a private jet and spent a further two hours at a clinic later in the day while doctors studied the results.

A statement on Manchester United's website then confirmed Rooney was now "in the care of the England medical team".

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"The expert independent medical view is that Wayne has a good chance of being fit after the group stage."

The statement added that the striker would have to be assessed carefully because "he will not have had the opportunity to play in less demanding games".

England have until 1400 BST on Friday - 24 hours before their opening game against Paraguay - to decide whether to include Rooney in the squad.

But Football Association sources have told the BBC that the decision has already been made - and Rooney will be in Sven-Goran Eriksson's squad.

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Earlier, FA executive director David Davies had a broad grin on his face as he left hospital with Rooney before they drove to Manchester Airport.

Among the medical staff who were at the Whalley Range clinic where Rooney's foot was scanned were United doctor Tony Gill and physio Rob Swire, England team doctor Leif Sward and other specialists.

It is thought that a consultant from Fifa was also on hand in case of a conflict between the club and the FA.

It was also reported that United lawyers were there.

If, as expected, Rooney is officially named in the squad, the unfortunate Jermain Defoe of Tottenham, who had been on standby, would be sent back to England.