John McGinn and Scott McKenna will both miss Scotland’s Nations League double header against Croatia and Portugal through injury but goalkeeper Craig Gordon has returned to the group.
McGinn, 29, is expected to miss three or four weeks with a hamstring strain picked up in Aston Villa’s victory over Wolves last month and, unusually, is forced to sit out an international break.
Centre-back McKenna, 27, has missed Las Palmas’ last three matches with a hamstring issue. However, midfielder Ryan Gauld – who earned his first two caps as a substitute in September’s matches – makes the squad despite being absent for Vancouver Whitecaps in recent weeks.
There are first call-ups for Aberdeen full-back Nicky Devlin, Preston North End centre-back Liam Lindsay and West Ham United midfielder Andy Irving.
Scotland face Croatia in Zagreb on 12 October before Portugal visit Hampden three days later.
Cristiano Ronaldo’s 88th-minute winner in Lisbon last month consigned Steve Clarke’s side to consecutive defeats in Nations League A, after Poland also struck late to win 3-2 in Glasgow.
It means Scotland have won just once in their last 14 outings as Clarke contends with a series of injuries to key players with Arsenal’s Kieran Tierney and Brentford’s Aaron Hickey both still missing.
Bologna midfielder Lewis Ferguson is only just returning from a knee injury which he suffered in April.
It was thought goalkeeper Gordon, 41, might have played his last game for Scotland when he earned his 75th cap against Finland in June.
However, having been reinstated as Hearts’ first choice goalkeeper this season, Gordon is preferred to his club team-mate Zander Clark.