Wales lock Jake Ball will miss most of the 2016 Six Nations Championship because of a knee injury that will sideline him for 10 weeks.
The 24-year-old, capped 15 times by Wales, may require surgery after damaging the medial ligament in his left leg during the Scarlets' 27-26 Boxing Day defeat by Ospreys.
"He's got a bit of a tear and he'll see a consultant to get an accurate view," said Scarlets head coach Wayne Pivac.
"With any luck, it's just a rehab job."
Ball received treatment during the Boxing Day derby, but completed the match.
The Australia-raised lock last featured for Wales in the 54-9 World Cup win over Uruguay.
Wales begin their Six Nations campaign in Ireland on 7 February and conclude it with a home match against Italy on 19 March.