Scotland coach Frank Hadden faces a scrum-half crisis ahead of the autumn internationals which start next weekend.
Mike Blair is confirmed as his first-choice half-back and has been so impressive of late that he was named captain of the side for the trio of Tests in November.
The Edinburgh star was being pushed hard for his place, though, by Chris Cusiter and Rory Lawson.
But both the Perpignan No. 9s have been ruled out by injury, leading to a call-up for Glasgow's former Wasps man Mark McMillan.
Now McMillan has been injured in training, leading to Glasgow utility back Colin Gregor joining up with the Scotland squad for their warm weather training camp in Spain.
The Scotland coaches decided to enlist Gregor after McMillan sustained knocks to his shoulder and hip during training on Monday afternoon.
Gregor, the top scorer for Scotland 7s in IRB competitions, played in all three games for Scotland A during the Churchill Cup during the summer.
He could now find himself on the bench for the opener against New Zealand next Saturday if McMillan fails to recover from his knock.