Scotland will be without Alastair Kellock for the duration of their Six Nations campaign after the lock underwent surgery on an arm injury.
Kellock's club Glasgow confirmed on Monday that their captain would be out for about four months after injuring his arm during their Heineken Cup defeat by Cardiff recently.
The 32-year-old, who has 56 caps, joins fellow Glasgow and Scotland lock Jonny Gray on the sidelines.
"Gutted about the arm but unfortunately part of the job I've had a good run for the last few years.. be back soon enough," Kellock wrote on Twitter.
Warriors head coach Gregor Townsend, whose side face Edinburgh on Boxing Day and New Year's Day, said losing Kellock was a major blow for the club.
"We are all gutted for Al to be missing out on playing for the next few months, but especially the 1872 Cup games," he explained.
"He has played a prominent role in these games over the last few season and thrives against Edinburgh.
"We wish him well in his recovery and he still has a big role to play at the club as he works his way back to full fitness."
Meanwhile, Glasgow centre Mark Bennett has also been sidelined for several weeks with a fractured toe, which was sustained on Scotland Sevens duty in South Africa earlier this month.
He does not require surgery but is expected to be out for several weeks.