A Melbourne man infected with coronavirus attended the Boxing Day sales at Chadstone Shopping Centre and day two of the Australia-India cricket Test at the MCG.
Just where the man acquired his infection is a mystery.
Acting Premier Jacinta Allan said health authorities don't believe the man in his 30s was infectious during his visit to the MCG on December 27.
But people seated in the Great Southern Stand's zone 5 between 12.30pm to 3.30pm have been asked to get tested and self-isolate.
"Anyone who was seated within that zone 5 bubble will be receiving a text message in the next couple of hours, advising them of the situation," Ms Allan said on Wednesday.
A day before, the man attended the Boxing Day sales at Chadstone Shopping Centre from 6am to 2pm.
He developed symptoms on December 30 and contact tracing has revealed he had stayed home and self-isolated since New Year's Eve.
Deputy Chief Health Officer Allen Cheng said it was a mystery case.
Both the MCG and Chadstone Shopping Centre have now been listed as potential exposure sites.
Testing boss Jeroen Weimar estimates this will affect the 7000 to 8000 fans who attended the Test and the "thousands" of people at the busy Chadstone Boxing Day sales.
Victoria recorded three new coronavirus infections on Wednesday, with just one coming from a local source and the other two acquired overseas.
It takes the number of active cases in the state to 41.
Testing lifted for a third straight day, with 37,509 swabs processed on Tuesday.
Victoria's list of exposure sites has almost hit 100, with two clothes retailers and a Sri Lankan restaurant in Melbourne added late on Tuesday.
A known case shopped at the Nike Company in South Melbourneon December 30 from 12:00pm to 12:45pm. Anyone in the store at this time must get tested and quarantine for 14 days.
Other health alerts have been issued for anyone at Melbourne's Culture Kings store on Russell Street and Tamarind 8 in Narre Warren at specific times.
They are asked to monitor for symptoms and get tested if they develop.
The Victorian government also announced on Wednesday that the return-to-work plan for the public service will be paused for a week.
The current outbreak linked to a Black Rock restaurant in bayside Melbourne, seeded from outbreaks in NSW, prompted the call for a review on Tuesday night.
The public service was due to move into the next phase of return to work from Monday - increasing office capacity to 25 per cent, ahead of a jump to 50 per cent on February 8.
© AAP 2021
Photo: Acting Victorian Premier Jacinta Allan (AAP Image/James Ross)