Gloucester centre Matt Scott and uncapped Edinburgh prop Murray McCallum have joined Scotland's two-day training camp in St Andrews early this week.
Scott has been brought in as cover for Edinburgh's Phil Burleigh, who injured his shoulder in his club's pre-season friendly against Sale Sharks on Friday.
McCallum, 21, replaces London Irish prop Gordon Reid, who sustained a concussion in a friendly against Ealing Trailfinders, also on Friday.
Reid will stay in the care of his club.
The training camp forms part of head coach Gregor Townsend's preparations for Scotland's autumn Tests against Samoa, New Zealand and Australia in November.