Match referee David Boon has Tested positive for COVID-19 and will not be available for the fourth Ashes Test in Sydney from January 5, Cricket Australia said.
Boon, who is asymptomatic and fully vaccinated, would be replaced by Steve Bernard, a New South Wales-based member of the international panel of referees, CA added.
Boon will remain in Melbourne, where he will complete 10 days quarantine, and is expected to be available for the fifth Test between Australia and England in Hobart, which begins on Jan. 14.
Amid a growing number of infections in Australia, Thursday's Big Bash meeting between Perth Scorchers and Melbourne Stars has been postponed after a member of the Stars support staff returned a positive Test.
England coach forced to isolate, to miss 4th Ashes Test
England head coach Chris Silverwood will miss the fourth Ashes test in Sydney next week after a family member tested positive for COVID-19 and he must isolate for 10 days, the England and Wales Cricket Board said in a statement on Wednesday.
The fourth Test is due to start next Tuesday with Australia having already retained the Ashes, leading the series 3-0 with two matches to play.
"Following the latest round of PCR tests administered to the England men's touring party on Wednesday 29 December, one family member has tested positive," the ECB statement read.
"As a result of the positive test, England men's head coach Chris Silverwood will have to isolate for 10 days, along with his family, in Melbourne and will miss the fourth Ashes test."
England have struggled with a COVID-19 outbreak that was discovered before the start of the second day of third test in Melbourne. Seven positive cases - three support staff and four family members - have been found in the camp this week.
England and Australia players were cleared to play day three in Melbourne after all testing negative for COVID-19, with the hosts seeing out the victory by an innings and 14 runs to retain the urn.
A fourth successive round of PCR tests will be administered on Thursday. Both England and Australia are due to fly to Sydney via a chartered flight on Friday morning.