Colin Charvis expects to be out of action for up to three weeks

Vice-captain Charvis needs a further two weeks' treatment to his ankle and Williams needs to rest a neck injury.

"Colin's injury is worse than we thought and Martin has a disc problem," confirmed coach Mike Ruddock.

The injuries leave Wales short of an experienced open-side flanker for the 5 February match with England in Cardiff.

Wales coach Mike Ruddock has called Ospreys' Richie Pugh and Blues' Robin Sowden-Taylor as back row cover.

Uncapped Pugh is now a strong contender for the number seven shirt, and Ruddock says he has plenty of faith in the 21-year-old's ability.

"Richie has been outstanding for the Ospreys and Wales U21s," said Ruddock.

The prognosis is that I could be out for another two to three weeks Wales flanker Colin Charvis

"In terms of his overall fitness and speed he has some of the best stats in world rugby.

"Our fitness coach Andrew Hore assures me this guy is quite exceptional in terms of number sevens already, and that gives you confidence."

Pugh toured with the squad to Argentina and South Africa in the summer, but the loss of Charvis is a massive blow for Wales.

He was outstanding in the autumn internationals and has continued his fine form with influential performances for club side Newcastle Falcons.

His ankle ligament injury stems from a Heineken Cup match against the Dragons on 16 January.

Wales had been relatively confident Charvis would recover in time to face England, but the former captain revealed the injury has been slow to respond to medical treatment.

We can't do anything to change it so we've got to move on Wales coach Mike Ruddock

Charvis said: "This is obviously a huge disappointment, but all I can do is continue with the programme of rest and treatment the Wales team doctors have prescribed for me.

"The injury has not responded as quickly as I had hoped and the prognosis is that I could be out for another two to three weeks.

"I'll just get my head down now and hopefully see the rest of the guys do well until I can return."

Ruddock admitted the injuries are a significant blow to his side's chances of beating England in Cardiff for the first time since 1993.

But he said: "England have lost people like Jonny Wilkinson, Mike Tindall and Martin Corry so it's one of those things we've got to take on the chin.

"We can't dwell on it. We can't do anything to change it so we've got to move on."