Defensive duo David Bates and Michael Devlin have been called up for Scotland's upcoming Euro 2020 qualifiers against Russia and Belgium, replacing Grant Hanley and Liam Palmer in the squad.
Centre-back Bates, who is currently on loan at Sheffield Wednesday from German side Hamburg, could be set to earn his fifth cap for his country over the international break.
His club team-mate at Wednesday, Liam Palmer, has been suffering from a back problem, but played in the Owls' latest fixture, a 2-1 defeat to QPR in the Sky Bet Championship on Saturday.
Meanwhile, Aberdeen defender Devlin is yet to make his debut for the national side.
Grant Hanley (groin) is sidelined until mid-September after picking up an injury prior to Norwich City's Premier League defeat against West Ham.
Scotland boss Steve Clarke had already lost centre-backs Stuart Findlay, John Souttar and Scott McKenna to injury before announcing his side for the Euro 2020 qualifiers at Hampden Park.
His 24-man squad for the upcoming internationals includes West Ham midfielder Robert Snodgrass, who has not featured for the national team since September 2018.
Clarke said he wanted to allow Celtic's Leigh Griffiths "a little bit more time" prior to giving him a Scotland recall after "a very difficult spell in his life", regarding the forward's recent battle with depression.
Watch Scotland vs Russia live on Sky Sports Football on Friday September 6 from 7.30pm.