Mike Ruddock last night admitted Wales' hopes of retaining their RBS 6 Nations title had suffered another telling blow with the loss of prop Chris Horsman.

The Worcester tight-head will undergo ankle surgery on Thursday to correct a long-standing problem and is unlikely to play again this season.

Horsman, who qualified to play for Wales on residency grounds last October, emerged as an integral part of Ruddock's Six Nations plans after breaking into the side during the autumn internationals.

Ruddock has already lost Grand Slam stars Brent Cockbain, Ryan Jones and Kevin Morgan to injury, while Tom Shanklin remains a major doubt as he continues to recover from a knee problem.

Ruddock is also waiting on Gavin Henson, who is currently banned for Wales' first three championship games but faces an appeal panel in Dublin tonight.

Horsman had been playing through the pain since October and the decision was taken yesterday that surgery could not be delayed any longer.

"The news comes as a blow to our ambitions to retain the Six Nations title," said Ruddock. "Chris Horsman came through the autumn Tests with flying colours. His positive attitude to the scrummage rubbed off on other players and his work outside the scrum was also impressive.

"The news should give other players the chance to go all out to prove themselves ahead of the Six Nations campaign. As with all injuries, it is a chance for players to grab the opportunity and try to hang onto the red jersey if they get it."

Adam Jones, a member of last year's Grand Slam side, is the obvious replacement and Ruddock will at least have Lions prop Gethin Jenkins back in action.

But Wales will miss Horsman's raw power, particularly in their Six Nations opener against England and Andrew Sheridan at Twickenham.