Craig Gordon has earned a Scotland recall despite not featuring for Hearts this season.
The 42-year-old last played for Hearts on May 3 and missed Scotland's June friendlies and opening World Cup qualifiers because of a slipped disc in his neck.
The goalkeeper was back in full training earlier in September but was not considered for Hearts' squad on Saturday after picking up a minor hamstring issue.
However, he has replaced Tynecastle team-mate Zander Clark in Steve Clarke's group for the upcoming World Cup qualifiers against Greece and Belarus.
Defenders Max Johnston and Dom Hyam have also dropped out of Clarke's 23-man squad.
Former St. Johnstone keeper Clark recently lost his place in the Hearts team to new German recruit Alexander Schwolow, and it is Gordon who joins Angus Gunn and Liam Kelly in the squad.
Gunn kept two clean sheets as Scotland opened their campaign with four points from away games against Denmark and Belarus last month, but is yet to make his Nottingham Forest debut. Kelly has only played once for Rangers this season, against Alloa.
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Clarke has named a settled squad for the Hampden double-header, with nobody coming in to replace defenders Johnston and Hyam.
Johnston started in Scotland's 2-0 win over Belarus and has played every minute of Derby's three games since then. Wrexham defender Hyam played 90 minutes against Derby on Saturday.
Anthony Ralston and Kieran Tierney are included after dropping out of the previous squad with injury.
