Ben Foster's hopes of ousting Edwin van der Sar as Manchester United's first-choice keeper next season are in tatters after it was confirmed the England international requires surgery on a cruciate knee ligament injury.

The 24-year-old had been suffering knee problems during the latter half of last season, which he spent on loan at Watford.  And he pulled out of the England B international with Albania at the back end of last month to undergo tests.

Now Foster's worst fears have been realised, with United releasing more specific details of an injury which will keep sidelined for months.

"Ben Foster has a cruciate ligament injury in his right knee and will require an operation in two to three weeks' time," a United spokesperson said.

In a statement, the club added: "The injury was then jointly assessed by United and England's medical staff after the goalkeeper reported for international duty at the end of May.

"While the Reds' medical staff have not put a timescale on the 24-year-old's return to action, he is likely to spend a lengthy spell on the sidelines."

It is almost certain to be the early months of 2008 before Foster is in action again.

The injury is a bitter blow to Foster, who has been outstanding in two seasons at Watford and had already spoken optimistically about his chances of succeeding Van der Sar as Alex Ferguson's number one for the Premiership champions next term.

If Foster had succeeded in that aim, he could easily have been vying with Paul Robinson for the England slot as well.  Instead, the former Stoke man now faces months of rehabilitation.

While he will be bolstered by the knowledge plenty of United players, including Roy Keane, Ruud van Nistelrooy and Wes Brown, have battled back from similar injuries, it is still a hugely disappointing way to end the campaign.

The news also means Tomasz Kuszczak, who spent last term as Van der Sar's understudy, is now virtually certain to remain at Old Trafford rather than go out on loan as some pundits had predicted.  PA