Adam Hastings looks likely to miss the Six Nations, adding to Scotland's injury problems in the lead-up to the tournament, which starts next month.
The fly-half damaged his shoulder while playing for Gloucester in their English Premiership defeat away to Leicester on December 24.
A statement on the club's website on Thursday revealed that Hastings will require surgery, while head coach George Skivington said earlier this week: "He will not be back any time soon".
The match against Leicester was the 26-year-old's first outing since he suffered an injury while playing for Scotland against Fiji on November 5, paving the way for the recall of Finn Russell.
Hastings' absence leaves Scotland thin on the ground for options at stand-off, with Blair Kinghorn now the only back-up to Russell with notable international experience at number 10.
Glasgow's Ross Thompson, who has featured in recent squads, is battling his way back from ankle surgery while Munster fly-half Ben Healy, who is Scotland qualified and due to join Edinburgh next season, has been touted as a potential option.
Hastings' lay-off is a further blow to coach Gregor Townsend as he prepares to name his squad this month.
Zander Fagerson, Darcy Graham and Hamish Watson – all of whom would be expected to start if fully fit – are working their way back from injuries and deemed doubtful for the start of the tournament.
Scotland launch their Six Nations campaign against England at Twickenham on February 4.