Victoria has recorded four new coronavirus cases and two are under investigation to see whether or not they could be false positives.
Premier Daniel Andrews on Friday confirmed two of cases are "low positive results".
"Further testing and examination is underway to determine whether they are in fact false positives," he said.
The other two cases are also under investigation to see if they are linked to known outbreaks.
The four cases are in the local government areas of Brimbank, Hume, Greater Dandenong and Wyndham.
Victoria's Chief Health Officer Brett Sutton said one of the infected persons had travelled in Deer Park and encouraged anyone in the area with symptoms to get tested.
"Until we know more about the potential exposure sites, potential movements of this individual and other close contacts that we can identify, I would encourage anyone who is symptomatic, especially in Deer Park, to look for a testing station nearby," Professor Sutton said.
No new deaths were reported on Friday, leaving the state's fatalities at 819 and the national figure at 907.
Melbourne's rolling new case average rose to 2.6, from 2.4, on Friday, but mystery cases in the two week to Tuesday dropped by half to two. The corresponding measures are zero for regional Victoria.
Some 23,583 Victorians got tested for COVID-19 on Thursday and Prof Sutton described them as "heroes".
"We can identify any last remnants of virus that might be circulating in Melbourne and we can end it. My enormous thanks to those individuals," he said.
Ahead of the weekend, Mr Andrews encouraged all Victorians to follow the rules when dining out and visiting friends and families.
"We're all in this together and we will all pay a price - all of us - one way or another if we don't play that part," he said.
"Following the rules - and I know the rules are not fun - but they're there to keep us open, they are there to keep us safe."
On-the-spot fines of $1652 for individuals and $9913 for businesses can be handed out for COVID-19 restriction breaches.
Victorians can report suspected breaches to the coronavirus hotline (1800 675 398) for Victoria Police, WorkSafe and authorised officers to follow up.
Australian Associated Press