Anybody who has been to Victoria can't enter Queensland without a 14-day mandatory hotel isolation period at their expense.
That complicated things for the three Queensland teams, Triple Eight, DJR Team Penske and Matt Stone Racing, in terms of travelling to Winton in northern Victoria for the July 18-19 event.
The circuit is some two hours north of Melbourne, where localised suburban lockdowns have begun to control rising case numbers, however the Queensland border control covers the entire state.
Motorsport.com understands the Winton round has, for now at least, been postponed rather than cancelled.
The Sydney switch will be confirmed by Supercars late tomorrow morning.
There is no word if the confirmed support categories, Super2/3, Carrera Cup and the Toyota 86 Racing Series, will also race at Sydney Motorsport Park.
SMP, which hosted the resumption of the season last weekend, was already locked in for two rounds on the revised 2020 schedule, with a December finale under lights.