Jones will miss all the August warm-up matches

Fly-half Jones has a partial tear in his left groin, ruling him out of Wales' three warm-up matches in August.

But the 29-year-old is expected to be back in full training at the end of the month, and should be available for Wales' World Cup opener on 9 September.

"This is magnificent news for us," said Wales coach Gareth Jenkins.

"It's just the tonic we need as we prepare for our warm-up games against England this week and Argentina and France at the Millennium Stadium later this month.

"Stephen is very much the lifeblood of this squad.

606: DEBATE Hook is our best 10, Alfie is our best captain JBOB1972

"He is a key leader and vital to us not just because of his rugby experience and what he offers on the pitch, but because of the impact he makes on the squad throughout our time together.

"He displays the sort of attitude that is reflective of the positive, enthusiastic and professional mood in the squad we have assembled - just the spirit we hope to take into the World Cup."

Wales captain Jones was injured in a warm-up game on Friday at the end of a week-long training camp in Brittany.

Fears grew on Monday that he would join Gavin Henson in missing the World Cup after a scan identified a torn muscle.

But another scan has showed it be to just a "partial tear", ruling out the need for surgery.

"Following a period of rest and recuperation, by next week he can start upping his rehab and get a progressive programme," said Wales physio Mark Davies.

"By the end of August he should be engaged in full training. It was in innocuous injury - there wasn't an actual incident - and we were initially surprised by the finding of the scan.

"But we all welcome the news we had on Wednesday that things are going to be OK."

Jones has been in competition with James Hook for the number 10 jersey, Hook starring in the Six Nations win over England when he replaced the injured Scarlets man.