Scotland lock Alastair Kellock will miss the Six Nations after he was ruled out for around four months following arm surgery.
Kellock has been forced to have the operation after injuring his arm whilst playing for the Glasgow Warriors in their 9-7 Heineken Cup defeat to the Cardiff Blues at Scotstoun on December 13.
The 32-year-old has been a regular starter for Scotland and joins fellow Glasgow and Scotland lock Jonny Gray on the sidelines.
Kellock, who has 56 caps for Scotland, wrote on his Twitter account: "Gutted about the arm but unfortunately part of the job I've had a good run for the last few yrs be back soon enough."
Warriors head coach Gregor Townsend, whose side face Edinburgh in a double-header on Boxing Day and New Year's Day, told the club's official website: "We are all gutted for Al to be missing out on playing for the next few months, but especially the 1872 Cup games.
"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."
The Warriors have also revealed that centre Mark Bennett has a fractured toe, which was sustained playing for Scotland 7s in South Africa.
He does not require surgery but is expected to be sidelined for several weeks.