Scotland centre Alex Dunbar is in danger of missing out on this year's World Cup after a training ground accident left him with ruptured knee ligaments.
The Glasgow back was due to start for the Dark Blues when they take on England at Twickenham on Saturday.
But the Scottish Rugby Union has announced he will now sit out the rest of the championships and potentially this year's World Cup - due to kick off south of the border on 18 September - after tearing his anterior cruciate ligament.
Matt Scott has now taken the 24-year-old's slot for this weekend's battle with the Red Rose while Dunbar faces up to the reality it will be six to nine months before he can think about adding to his 14 caps.
He was taking part in the team's final training session at Murrayfield before jetting south to London when he fell to the turf clutching his knee.
Dunbar was rushed to the near-by Spire Murrayfield Hospital for a scan, but the results only confirmed Scotland head coach Vern Cotter's worst fears.
Speaking before the severity of the injury was confirmed, the New Zealander said: "Alex was in a bit of discomfort. He just went down on his own. It was a change of direction and then he went down. It's very unfortunate and he's obviously upset.
"He will miss this Calcutta Cup game and we're hoping it's only a minor injury. We will have to wait and see.
"My worst fear is that it could be an ACL (anterior cruciate ligament). Hopefully it's not. If it is an ACL, it will be a fine cut [for him to make the World Cup]. But they are pretty good at getting these types of injuries back, if that is the case.
"It's not as severe as it used to be but certainly it would be a set back for Alex."
An SRU spokesman added: "Scottish Rugby would like to thank the superb professionalism of the Spire Murrayfield Hospital MRI staff, and consultant radiologist Dr Scott McKie, for the support and help in what was a time-pressured situation."
