Scarlets fly-half Rhys Patchell could miss the first four rounds of the PRO14 Rainbow Cup through a hamstring injury.
It leaves the Welsh region short of their Wales international but Sam Costelow has returned to fitness as well as Johnny McNicholl.
The hamstring injury comes a second blow for Patchell who played no part in the Six Nations after suffering a concussion against Scotland in the Autumn Nations Cup.
“To get another six to eight week setback is devastating for all of us,” said Scarlets head coach Glenn Delaney.
“He's approaching it like the guy he is and is outwardly optimistic and cheerful but I know deep down he's really disappointed he never got the chance to play because he was ready to play.
“He might be back for the back end of the Rainbow Cup but we'll do the right thing. If we can get him on the track then that would be great.”
Scarlets head into Sunday's European Champions Cup match against Sale with all of their Wales internationals back and available.
The return of key players for the last-16 tie at Parc y Scarlets has given Delaney a lot to think about as he ponders selection.
“The hardest thing we're going to do this week is select a team because it's a big challenge,” said Delaney.
“We've got some of those great headaches and I have had some of those 2am wake-ups. What are we going to do? How does that look?
“We're getting into really fine detail about how the way we want to play looks and who we want to deliver that.”
