Russell Martin and Kieran Tierney have withdrawn from the Scotland squad for the friendly double-header against Costa Rica and Hungary.
Rangers defender Martin has been struggling with a back problem and Celtic full-back Tierney missed the goalless draw against Motherwell on Sunday with a calf complaint.
Tierney's Hoops team-mate Jack Hendry, 22, has been drafted into Alex McLeish's squad for a first senior call-up, the Scottish Football Association has announced.
Celtic manager Brendan Rodgers hopes to have Tierney back for the home game against Ross County following the international break.
The Northern Irishman said: ``He had a slight issue with his calf towards the end of last week. We gave him through the week to see how he felt. It wasn't quite right.
``He couldn't play today and we'll see how he is for the Ross County game. He won't be travelling to Scotland.''
Scotland host Costa Rica at Hampden Park on Friday before facing Hungary in Budapest on March 27.