Wayne Pivac suffered an injury blow as new Wales squad member Josh Macleod limped off during the Scarlets' PRO14 clash with Glasgow on Sunday evening.
The flanker was named in a Wales squad for the first time in his career last Tuesday after an impressive year that had seen him top the PRO14 turnover charts last season.
But the 23-year-old will now be sweating after he was forced off injured after 29 minutes at Scotstoun.
The flanker, one of six back-rowers named in Pivac's squad for the six-game autumn schedule, looked in serious pain as he struggled to walk unassisted off the pitch following the injury.
On the TV coverage, commentators were hopeful it was nothing more than a dead leg, but with Wales due to meet up as a squad on Monday, any injury at this stage will naturally be a concern for Macleod and Pivac.
Were the flanker ruled out of the autumn, Pivac may look to Dragons' Taine Basham, Cardiff Blues' Shane Lewis-Hughes or Macleod's Scarlets team-mate James Davies as possible replacements.
Wales hooker Ken Owens was also forced from the field during the Scarlets' 20-7 defeat to Glasgow, being replaced by Ryan Elias after suffering a shoulder injury.
