Scarlets fly-half Rhys Priestland will undergo scans on Monday after sustaining an Achilles injury against Exeter on Saturday.
The 25-year-old was stretchered off early in the second half of the Heineken Cup clash after slipping while taking the ball into contact.
He could face an an extended period on the sidelines which will be a huge setback for the Llanelli-based region and Wales during next year's Six Nations.
"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."
There were more injury concerns for the Scarlets as Aaron Shingler and Samson Lee were also amongst the casualties.
Shingler, who impressed for Wales during the recent end-of-year Tests, 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."