Just when Manchester United appeared to be in rude health, the Barclays Premiership champions’ preparations for next season were dealt a significant blow yesterday when Ben Foster, the emerging England goalkeeper, was ruled out indefinitely with knee ligament damage. Foster will have surgery in the next two to three weeks and is likely to be out for up to nine months, although he could miss all of next season.

The injury constitutes a multiple blow for United, England and Foster, who had not only been expected to challenge Edwin van der Sar for the goalkeeper’s jersey at Old Trafford, but also Paul Robinson for the position of England No 1.

Foster had been troubled by a knee injury earlier in the year while playing for Watford, where he excelled on loan during the Premiership season just finished, and then aggravated the problem in the final weeks of the campaign. The injury was assessed by the United and England medical staff after the 24-year-old reported for international duty last month, but he was sent home three days before the B friendly against Albania at Turf Moor, Burnley, 13 days ago.

Now Foster’s worst fears have been realised, although he may take comfort from the knowledge that plenty of United players, including Roy Keane and Ruud van Nistelrooy, have battled back from similar injuries to rediscover their best form.

With Foster out of action, any thoughts Sir Alex Ferguson, the manager, might have given to loaning out Tomasz Kuszczak have been put on hold. The Poland goalkeeper joined United on loan from West Bromwich Albion last August, but the move will become permanent this summer.

Foster, who joined United from Stoke City for £1 million in July 2005, was loaned out to Watford and helped the club to win promotion to the top flight the next season. He was equally impressive in his 29 Premiership appearances for Watford, despite their relegation straight back to the Coca-Cola Championship.

Van der Sar was always going to start next season as United’s first-choice goalkeeper, but the Dutchman’s jittery displays towards the end of the title-winning campaign, coupled with Foster’s outstanding form for Watford and for England in the 1-0 friendly defeat by Spain in February, had convinced Ferguson that the youngster was ready to challenge for a starting berth.

There was some good news for United yesterday, with Nani passing a medical before being taken on a tour of Old Trafford. The Portugal winger is awaiting international clearance and it is expected that his projected £17.3 million move from Sporting Lisbon will be completed on July 1, when Owen Hargreaves, the England midfield player, will join the club from Bayern Munich.

Anderson, the Brazil midfield player, may have to wait until after the Copa America ends on July 15 before being granted a work permit that will allow him to complete his move from FC Porto to United. It was agreed that, as part of the deal, which could end up costing United as much as £20.4 million, the Premiership champions would give Porto preference for the loan of players, although the Portuguese club are expected to face competition from Claudio Ranieri, the new Juventus coach, for Giuseppe Rossi.

The 20-year-old United striker impressed under Ranieri at Parma, whom he joined on loan in January, scoring nine goals in 19 league matches. Rossi would prefer to stay in Italy if he is loaned out again, although Ferguson is thought to be undecided. Gerard Piqué, the 20-year-old Spanish defender who spent last season on loan at Real Zaragoza, could also be loaned out again.

United are exploring the possibility of playing a match in Guangzhou, China, on July 27 as part of their summer tour to Asia after the planned fixture in Malaysia on that date was cancelled.