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
Gemma Rowland has had a 'whirlwind' start to her international career with Wales. Despite losing to France, she is confident Wales Women can bounce back and claim a rare Triple Crown against Ireland on Sunday, as WRU TV's Graeme Gillespie discovers.
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.
Welsh players and management joined Deputy Minister for Sport Ken Skates at the Pierhead Building, Cardiff Bay earlier this week to reveal the Union's pioneering school-club hub initiative has been so successful the project will now almost double the scale of the original project.
The Scarlets, Newport Gwent Dragons, Cardiff Blues and the Ospreys look ahead to Judgement Day III which sees the Blues take on the Ospreys (2.30) and the Dragons tackle the Scarlets (4.45pm) at the Millennium Stadium tomorrow afternoon.
A look ahead to Judgement Day and back at youth finals day in the Principality Welsh Rugby Union Podcast. We hear from Andrew Coombs, Jake Ball, James Davies, Dan Lydiate and Josh Navidi. We also speak to Wattstown, Ystradgynlais, Rhydfelin, Pontypool United, Penallta and Pontypridd youth coaches at finals day at the Millennium Stadium.