Man Utd lapses a worry for Rio

Manchester United's Rio Ferdinand (L) avoids the tackle of Manchester City's Darius Vassell during the Premiership match at Old Trafford, Manchester, northwest England, December 2006. Ferdinand admits Manchester United's recent defensive problems are causing concern ahead of the crucial, closing stages of the season.

Rio Ferdinand admits Manchester United's recent defensive problems are causing concern ahead of the crucial, closing stages of the season.

Sir Alex Ferguson's table-toppers face Premiership bottom club Watford at Old Trafford on Wednesday anxious to keep a clean sheet for the first time since before Christmas.

A late lapse in the FA Cup fourth round victory over Portsmouth last weekend allowed Kanu to deflect Pedro Mendes's effort past Tomasz Kuszczak to end United's hopes of maintaining a shut-out for the first time in seven games.

Two goals from Wayne Rooney ensured the slip didn't affect the final outcome of the tie that set the club up for a fifth round date with Reading.

But United captain Gary Neville last week acknowledged that his team-mates cannot expect the side's firepower to deliver two or three goals every match.

And Neville's back-four colleague Ferdinand agrees that defensive improvements must be made if they are to maintain the six-point advantage over second-placed reigning champions Chelsea at the head of the Premiership table.

"We pride ourselves on clean sheets and we've not had one for a while," said the England centre-back.

"I thought we were heading for one against Portsmouth. It was disappointing to concede a scruffy one but the result is always the most important thing," Ferdinand added.

Watford will arrive in Manchester boosted by successive victories over Blackburn Rovers and West Ham United.

But Aidy Boothroyd's side will almost certainly have cause to regret Rooney's dramatic intervention as a second half substitute against Portsmouth.

United manager Ferguson admitted he had originally planned to rest the England forward for the visit of Watford but may be forced into a rethink after the striker's stunning 30-minute display.

With Cristiano Ronaldo set to return after a week-long holiday in Dubai and Louis Saha fit again after recovering from a knee problem, Watford are likely to face the full force of Ferguson's forward options.

And their cause will not be helped by the enforced absence of on-loan keeper Ben Foster after United denied permission for the youngster to line-up against his full-time employers.

Foster, who will be replaced by Watford veteran Alec Chamberlain, has been outstanding for the Premiership strugglers this season and Ferguson confirmed this week that the youngster will be returning to Old Trafford at the end of the current campaign.

"Without question, Ben will come back here," Ferguson said. "We know Ben has a good future in the game.

"He is doing well at Watford and, at his age, has everything in front of him, because I believe him to be England's best young goalkeeper."

With just two Premiership victories, Watford are seven points away from safety but Boothroyd's assistant Keith Burkinshaw admits he has been impressed at how the young manager has coped with a difficult season.

"It's not easy because I know what it is like when things are going wrong," said Burkinshaw. "I had a season at Tottenham when we were relegated - my first there - and you feel like committing suicide as it does get to you."

Boothroyd, meanwhile, hopes to complete the signing of Peruvian centre-back Luis Alberto Guadalupe from Universitario this week although the 30-year-old is unlikely to arrive from South America in time to face United.