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
Coach Richard Hodges is hoping Wales U20 can put a disappointing campaign behind them when they tackle Japan tomorrow as they look to finish the U20 Championship strongly to secure a good seeding for next year's tournament.
Wales U20 coach Richard Hodges is targeting three wins from three games in the Under 20 Championship after suffering defeat to England on Saturday. However, as WRU TV's Liz Jones discovers, he is concerned about the threat Japan pose tomorrow.
Wales defence coach Shaun Edwards is looking for physical and mental toughness from the 47-man World Cup training squad which was revealed yesterday and he added he is looking forward to seeing which players are prepared to dig the deepest.
Wales Under 18 captain Calum Haggett has received a conditional offer to read Biomedical Science at St Anne's College, Oxford. WRU chairman Gareth Davies went to meet Calum and Coleg y Cymoedd Principal Judith Evans to wish him luck in his exams and pass on some of his personal experience.
Cardiff Blues U18 Girls will go into Sunday's Gemau Cymru with an extra spring in their step after Welsh internationals Elinor Snowsill and Philippa Tuttiett offered some last minute tips at a training session earlier this week.
Wales U20 bounce back in the World Rugby Championships in this week's Principality Welsh Rugby Union Podcast. We hear from forwards coach Geraint Lewis and captain Ollie Griffiths, plus new WRU head of physical performance Paul Stridgeon. We talk new facilities in Usk and hear the plans of new Cardiff Blues head coach Danny Wilson.