Wales flanker Dafydd Jones will miss the rest of this season's RBS 6 Nations Championship due to a pelvic injury.
The Llanelli forward was a late withdrawal from Wales' starting line-up that took on Italy in Rome last weekend after aggravating a groin problem.
Jones has now been told he needs six weeks' rest, giving title contenders Wales more back-row injury trouble with Newcastle Falcons flanker Colin Charvis currently out nursing a foot problem.
"Dafydd has a pelvic condition known as osteitis pubis, which is currently preventing him from running," said Wales team physiotherapist Mark Davies.
Jones, who has won 27 caps, was replaced against Italy by Neath-Swansea Ospreys forward Jonathan Thomas as Wales completed the second stage of a possible Grand Slam by recording a 38-8 win.
Charvis, meanwhile, is not expected to be fit for Wales' next game - against France in Paris on February 26 - but he should start light training again shortly, and could feature during next month's RBS 6 Nations appointments with Scotland and Ireland.
Assessing Wales' current injury situation, Davies added: "Ryan Jones is progressing well with the A/C joint injury to his shoulder, and he is taking part in fitness and conditioning training this week.
"He will be reviewed, and subject to a fitness test, should be in contention for selection to face France.
"(Prop) Duncan Jones is set to be officially released to play for his region (Ospreys) after recovering from a broken thumb.
"(Centre) Sonny Parker's neck injury remains an issue, and he is not currently involved in any contact training. He will be continually monitored and will be tested again next week to verify his fitness.
"Hal Luscombe left the field against Italy with a hamstring injury, but he is responding to treatment this week and will hopefully progress to making himself available."
Wing Luscombe limped off in the second-half at Stadio Flaminio and was replaced by his Newport Gwent Dragons colleague Kevin Morgan, who is favourite to start in Paris if Luscombe misses out.
Andy Farrell admits the process of selecting England's 50-man training squad ahead of the World Cup was rigorous - but the backs and defence coach also revealed how tough it was to leave some stars out.