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
Glyncoch have had a remarkable past couple of seasons, having lost just once in the last two seasons. Their fine form has been capped by claiming the South Central Division 5 crown of the SWALEC League.
With two rounds of the HSBC Sevens World Series remaining, Wales head coach Paul John has sprung a few surprises for this week's penultimate round in Glasgow. And there's still plenty to play for with World Cup spots on the line.
All roads lead to Sardis Road tomorrow as Pontypridd host Llanelli in the Principality Premiership Play-off final. WRU TV's Graeme Gillespie and Alex Bywater are joined by Ponty's Dale MacIntosh and Rhys Shellard along with Llanelli's Kevin George and WRU's Will Thomas.