Wales hooker Ken Owens faces a battle to be fit for the start of the Six Nations after having shoulder surgery.
The 33-year-old is expected to be out for between three and four months after suffering the injury against Glasgow.
Uncapped flanker Josh Macleod is also expected to be absent for a couple of months because of a hamstring problem suffered in the same game. He is targeting a return to play in December.
Owens has been an constant in the Wales side for a number of years, becoming his country's most-capped hooker last year.
However, Wales now face starting their Six Nations campaign - if it is held as scheduled - against Ireland on 7 February without him.
Owens had come on as a second-half replacement in the 20-7 defeat at Scotstoun before leaving the field himself after taking a knock following a quick tap penalty.
The injured pair were released from the Wales squad after being ruled out of the 2020 international campaign.
Dragons hooker Elliot Dee and Scarlets flanker James Davies have been called up to the squad in their place, with Dee joining Ryan Elias and uncapped Sam Parry as Wayne Pivac's hooker options.
Those three now have six fixtures to potentially cement their place as a starter ahead of the Six Nations.
As for the Scarlets and coping without two more injured players, they have four Champions Cup matches in December and January, while the Pro14 Welsh derbies are scheduled around Christmas and new year.
