The Academy graduate underwent a scan on his ankle on Monday and has withdrawn from Steve Clarke's squad for the internationals in Cyprus on Thursday and at home to Kazakhstan on Tuesday.
McTominay was initially hurt during the Europa League victory over Partizan Belgrade last Thursday but was fit enough to maintain his 100 per cent record of playing in this season's Premier League, for the visit of Brighton & Hove Albion.
In the closing stages of our 3-1 win on Sunday, McTominay went down in pain, clutching his ankle, and, although not requiring the stretcher that was brought onto the field, he still needed assistance to hobble off.