Celtic and Rangers will both play four days before Scotland’s Euro 2020 play-off against Israel after having Scottish Premiership games pushed back.
A full top-flight card had been scheduled for next Friday to give Scotland head coach Steve Clarke extra preparation time for the 8 October tie.
But the Old Firm have progressed to Thursday’s Europa League play-offs.
So Celtic are now away to St Johnstone at 12:00 BST a week on Sunday, with Rangers hosting Ross County at 15:00.
Five Old Firm players featured in Clarke’s squad for the opening Nations League double-header earlier this month.
Scotland face Israel for in a one-off tie, with the winners then taking on Norway or Serbia for a place at next summer’s rearranged Euro 2020 finals.