Lawrence Shankland is the latest player to pull out of the Scotland squad.
The Dundee United striker has been replaced by Kilmarnock striker Eamonn Brophy.
Steve Clarke's troops have been ravaged for the latest double-header - the first game of which they won 2-1 on Saturday afternoon.
Andy Robertson, Ryan Fraser, Liam Cooper and Scott McTominay all recently pulled out due to injury.
Shankland, 24, withdraws despite the likelihood of playing in Tuesday evening's Kazakhstan match in Glasgow.
Brophy - who played under Clarke at Kilmarnock - made his senior Scotland debut against Cyprus back in June.
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