Glasgow lock Tim Swinson will miss Scotland's autumn Tests after being ruled out for around six months.
Swinson, 31, was forced off early in the Scots' final summer Test win in Argentina after landing heavily on his knee when claiming a restart.
He has had surgery on his leg since returning home and will now miss the first half of next season.
Swinson started the defeat by USA at blind-side before reverting to lock for his 38th cap against Argentina.
The former Newcastle second-row was also sidelined for four months last season after suffering a hand injury in Scotland's first autumn Test against Samoa, which required surgery and kept him out of the first half of the Six Nations.
Scotland are already without captain John Barclay, who hopes to return in time for the 2019 Six Nations after rupturing his Achilles tendon.