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Ferdinand walks off the pitch after picking up the injury.

The injury setback could have been a significant blow to Ferguson's hopes of retaining United's English and European crowns as Ferdinand was thought to be out for the Premier League fixtures against Middlesbrough, Manchester City, Wigan and Arsenal, as well as next week's semi-final second leg at the Emirates.

He will miss United's Premier League game with Middlesbrough on Saturday but manager Sir Alex Ferguson is confident he could be fit to face the Gunners.

''It's good news with Rio. It is not a cracked bone, he had a bit of bruising on the lung which was why he was coughing up *lo** but there has been nothing since then,'' Ferguson said.

''Hopefully we can get him ready for Tuesday, he seems almost back to normal. But he won't play tomorrow.

''Of course when you see it at the time you fear the worst but now it is just a case of getting him back training, hopefully on Sunday, and getting him ready for Tuesday.''

Ferdinand was allowed home in the early hours of Thursday morning after being assessed at a Salford hospital, undergoing tests to determine whether he had suffered a punctured lung.

He left the field on Wednesday cl**tching his right side after he ran into Eduardo, and moments later he was sandwiched between keeper Edwin van der Sar and Nicklas Bendtnercontesting a high ball.

"Rio is desperate to play but he'll take medical advice and won't jeopardise anything to the detriment of the team," said a source close to the player.

"He was in a bad way after the injury but it was typical of him that he wanted to come straight back on and didn't know he'd already been subbed."