The former West Ham and Leeds defender, 24, is now due to have surgery next week.

Following an examination by club medical staff Friday, United said in a statement on their official website: "Rio Ferdinand's left knee was examined today and following discussions between the Manchester United medical team and the England doctor it was felt to be in Rio's best interests that he undergo an arthroscopy (keyhole surgery) at the beginning of next week.

"As a result, he will be unavailable for the next two England games."

England coach Sven-Goran Eriksson said: "We are very disappointed to lose Rio Ferdinand but this is obviously the right decision for medical reasons.

"I would like to emphasise the excellent co-operation between Manchester United and ourselves over this issue."

Eriksson will not be calling up a replacement for the matches at Middlesborough and Leicester respectively.

Ferdinand, who became Britain's most expensive player when he joined United for 29 million pounds (46 million dollars) from Leeds in 2002, sustained the injury while playing for England in Durban during last week's friendly win over South Africa.

But there was better news for Eriksson and England when Everton said Friday their teenage forward Wayne Rooney would be fit for the Serbia-Montenegro match.

In a statement on their official website, Everton said that having examined the teenage forward's knee injury following his return from England's training camp at La Manga, Spain, they were satisfied he was fit.

Everton physiotherapist Mick Rathbone said: "We have checked Wayne out today. He has trained in the past few days and reported no reaction so he will join up with the squad on Sunday."

The Goodison Park club's announcement will come as a relief to Eriksson following the club v country row over Rooney's international availability that the Swede has had with Everton manager David Moyes.

Rooney, 17, sustained the injury during the 2-1 league defeat by Manchester United earlier this month and after the game Moyes confirmed he was withdrawing him from the South Africa trip.

However, the Football Association insisted on verifying Rooney's fitness for themselves following statements by Moyes that he did not want his young striker playing too many matches.