The Manchester United manager, Sir Alex Ferguson, has announced that Wayne Rooney is unlikely to be fit in time for the start of the season after picking up a virus in Nigeria which has left the striker unable to train. Ferguson also stressed today that Cristiano Ronaldo would be staying at the club, despite continued interest from Real Madrid.

"I doubt we'll get Rooney fit for the start of the season with the virus he's had," said Ferguson, who is facing up to a selection headache ahead of the new season. "It's a virus he picked up in Nigeria and it's not a nice one, but quite a few have had it. It's such a bad virus and he's got to be training to be fit."

Rooney did not play in the 2-1 friendly win against Portsmouth in the Nigerian capital, Abuja, on July 28 - a game for which his club reportedly received £2m. Ferguson was forced to defend the fixture against critics who argued that the 10-day tour of South Africa and the journey to Nigeria would drain the players ahead of the new season.

In addition to Sunday's Charity Shield clash against Portsmouth, the England international is also likely to miss United's Premier League opener against Newcastle the following week. It is deeply frustrating for Rooney, who also saw his start to last season disrupted by injury when he suffered a broken metatarsal against Reading on the opening day of the 2007-08 campaign.

The news will come as a major blow to United, who will also begin the defence of their title without injured winger Cristiano Ronaldo, who underwent ankle surgery earlier this summer and is not expected to return to action until October. "I don't know whether we will have a team ready," admitted Ferguson. "Nani is suspended, Anderson is in the Olympic Games. [Michael] Carrick's come in this morning and he may play a part of the game on Sunday."

Regarding the ongoing Ronaldo transfer saga, Ferguson responded: "The matter is closed now. He is a Manchester United player, it's finished. He is going to play here, believe me."