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
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The Wales teams return home for the Irish leg of their Six Nations campaigns in this week's Principality Welsh Rugby Union Podcast. We speak to Wales attack coach Rob Howley and defence coach Shaun Edwards, as well as flanker Dan Lydiate and full back Leigh Halfpenny. We hear from Wales Women's back rower Sian Williams and Wales U20 forwards coach Chris Horsman and flanker Ollie Griffiths.
Wales look to build on victory in Paris in this week's Principality Welsh Rugby Union Podcast. We hear from coach Warren Gatland and captain Sam Warburton, as well as Wales Women's coach Rhys Edwards. We also hear from Wales U20 duo Dan Jones and Joe Davies, along with Wales U18s.
We look ahead to the French tests in this week's Principality Welsh Rugby Union Podcast. We look ahead to Wales France with Warren Gatland, Sam Warburton, Scott Baldwin, Rhys Webb and Jonathan Davies. Wales Women are the only team in red still unbeaten in this Six Nations, we speak to captain Rachel Taylor. Wales U20 are looking bounce back from defeat in Scotland, we hear from coach Jason Strange, captain Rory Thornton and front rower Dillon Lewis.
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.
We get a special concussion briefing from the top in this week's Principality Welsh Rugby Union Podcast. WRU national medical manager Prav Mathema explains the ins and outs of concussion for all levels of Welsh rugby, Dragons captain Rhys Thomas looks ahead to their European semi-final in Edinburgh, while we also hear from more of the clubs in the semi-finals of the SWALEC Cup Bowl and Plate.