Former Australian cricketer now ICC Match Referee David Boon has tested positive for COVID-19.
Boon who is believed to be asymptomatic is now forced to isolate and will miss the fourth Test match at the SCG.
He should be right to return for the final Test of the summer in his home state of Tasmania.
Boon who is double vaccinated and had also received a booster shot will be replaced by Steve Bernard.
It comes just hours after England coach Chris Silverwood was ruled out of attending the fourth Test due to a family member testing positive.