Wales fly-half Sam Costelow is set to be on the sidelines until the new year following shoulder and hamstring injuries.
The 22-year-old sustained the injury in Wales' recently concluded game against Barbarians last weekend where he went off at half-time.
He is expected to take the fly-half role for Wales in the upcoming Six Nations tournament following the retirement of Dan Biggar.
Scarlets head coach Dwayne Peel said they are expecting Costelow to be out of action at least until January.
“We are not expecting him in the short term,” said Peel.
“It will be beyond Christmas, beyond the new year before we see him. I haven’t an exact date. We are still waiting on the final prognosis and some specialist opinion, really, on that.
“It is a disappointing one for us because he is going to be out for the large part of the first half of the season.
“There is loads more to come from him, and this is obviously a setback in his career at the minute to have this injury.”