Rhys Priestland will have scans today as Wales and the Scarlets sweat on the fly-half's fitness.
The 25-year-old was stretchered off with an Achilles injury after 47 minutes of the Scarlets' home defeat to Exeter Chiefs.
Priestland slipped while taking the ball into contact and could face an extended period on the sidelines.
"Rhys has got an Achilles injury," said Scarlets head coach Simon Easterby.
"We won't know the extent of that until he has a scan. But it didn't look good."
The Scarlets' woes were compounded by further injuries suffered by Aaron Shingler and Samson Lee.
Shingler, a shining light in Wales' autumn campaign, came off with a groin problem while Lee injured his shoulder.
"Aaron Shingler suffered a groin injury and he's been carrying that for a couple of weeks," added Easterby.
"Hopefully he will come through but that didn't look great either."
The injured trio are just the latest worries for Rob Howley ahead of the 2013 RBS Six Nations.
Adam Jones, Aaron Jarvis, Craig Mitchell, Ian Evans, Alun Wyn Jones and Dan Lydiate all remain on the sidelines, as do George North, Leigh Halfpenny and Jamie Roberts.
But Roberts and Halfpenny are both set to be fit for the Championship with return dates pencilled in for mid-January.
"We've had a few opinions now from the specialists and it seems to be about six weeks will be there time where the nerve will have settled down and it'll be safe to go back to play," added the Cardiff Blues full-back
Warren Gatland and Sam Warburton look ahead to this week's crunch RBS 6 Nations tie against France, where the Wales skipper in particular is keen to make his mark, as Paris has proved a bleak place for him in the past.
Reaction from Scotland and a special focus on Welsh Women's rugby in this week's Principality Welsh Rugby Union Podcast. We hear from Wales captain Sam Warburton and coach Warren Gatland, as well as Wales U20 reaction from forwards coach Geraint Lewis, along with Josh Adams and Olly Griffiths. There is also a special focus on Welsh Women's rugby with coach Rhys Edwards, as well as hearing from clubs Bedlinog, Penybanc, Kidwelly and Skewen. We also speak to volunteer of the year, Sue Davies on Whitland and the Scarlets.
Following their historic win over England, Wales Under 20 suffered a narrow, 36-34 loss to their Scottish counterparts last weekend, despite outscoring them by five tries to three. Watch the match highlights and reaction.
Disappointment at the Millennium Stadium, but don't be sad because two out of three is not bad in this week's Principality Welsh Rugby Union Podcast as the 20s and Women both win. We hear from Sam Warburton, Dan Lydiate, Alun Wyn Jones, Jamie Roberts and Leigh Halfpenny about the defeat to England and looking forward to Scotland. Wales U20s captain Ollie Griffiths, back Josh Adams and forwards coach Geraint Lewis talk about their victory over double world champions England, while Wales Women also beat a world championship winning England team - we speak to backs Elinor Snowsill, Ade Taviner and Laurie Harris.
England coach Stuart Lancaster gives his verdict after seeing his skipper Chris Robshaw lead his side to victory against Wales at the Millennium Stadium in the opening game of the RBS 6 Nations championship.