Worcester forward Horsman faces ankle surgery later this week, and he is likely to be sidelined for around five months.

Horsman, 27, made his Wales debut off the replacements bench against New Zealand in November, and then started Tests against Fiji, South Africa and Australia.

The powerful scrummager was an integral part of Ruddocks RBS 6 Nations plans, but he now becomes the latest Welsh injury casualty.

Back-row forward Ryan Jones, lock Brent Cockbain and full-back Kevin Morgan, who all played key roles in last seasons RBS 6 Nations Grand Slam triumph, have already been ruled out of the tournament, while centre Tom Shanklin is also likely to miss all five games.

Gavin Henson is currently banned for the opening three matches, although he will appeal against a 10-week suspension in Dublin on Tuesday for elbowing Leicester prop Alex Moreno during a European Cup clash between the Ospreys and Leicester last month.

Wales kick off their RBS 6 Nations campaign against world champions England at Twickenham on February 4.

Worcester have confirmed Horsman will undergo surgery on Thursday, having suffered with an ankle problem since October.

Chris has been playing through the pain from his ankle for some time now, and the point has been reached where surgery is the only real option, said Warriors rugby director John Brain.

It is a blow for us, but not an unexpected one - and we have enough quality props at the club to deal with the situation.

Until the surgery has been completed, we cant be sure exactly how long he will be out of the game. But we will do everything we can at the club to ensure that his recovery will be complete.

Former Bath prop Horsman qualified to play for Wales earlier this season, having completed a three-year residency period.

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

"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.

"It's a big blow to Wales but I really feel for Chris who had only just broken into the team. It must be very disappointing for him on a personal basis.

"We wish him a complete recovery, bearing in mind that we also have him in our mid to long term plans with the World Cup in mind.

"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 with both hands 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 British & Irish Lions prop Gethin Jenkins back in action.

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

Horsman made an immediate impact for Wales. He was sin-binned at a crucial time in the defeat to South Africa last November and was warned by Ruddock over his conduct.

He responded by turning in a powerful display the following week as the Welsh pack overpowered Australia at the Millennium Stadium during a famous 24-22 triumph.