Wales full-back Liam Williams has been ruled out for up to six weeks with a hamstring injury.
The 24-year-old suffered the setback in Wales' final RBS 6 Nations clash against Italy on March 19 and was forced to sit out club side Scarlets' derby against Ospreys on Saturday.
Scarlets head coach Wayne Pivac confirmed the lay-off could sideline Williams for the rest of the Guinness PRO12 season.
"Four to six weeks is what we're told, don't expect to see him in the next few weeks," said Pivac, whose side face Munster on May 7 in their final regular season game.
Williams has made just one PRO12 appearance for Scarlets this season, after returning from the ankle injury he aggravated during the World Cup, before returning to Wales duties for the Six Nations.
Pivac added: "We've had 60 minutes from him so far this season which is disappointing but there's no one more disappointed than Liam.
"We just have to get him right for the latter part and who knows there may be more rugby to come"
Pivac also confirmed that centre Scott Williams, who suffered a knee injury in Wales' World Cup win over England in October, is expected to make a return to action for Scarlets at the end of April.
Both will be hoping to feature in Wales' Test against England on May 29 before June's tour to world champions New Zealand.