Melbourne and regional Victoria will still move to eased restrictions despite the source of four new local COVID-19 cases being unknown.
Acting Premier James Merlino confirmed the easing of restrictions will proceed as planned from 11:59pm on Thursday, with one slight change for Melbourne.
Masks were set to become non-compulsory outdoors but now will have to be worn outdoors under all circumstances.
"It is inconvenient but an easy thing to do," Mr Merlino told reporters.
"We are used to it, we know it works."
Deputy Chief Health Officer Allen Cheng said the four cases, all from the same household in Reservoir, were not primary close contacts and had not visited any listed exposure sites.
"While we can't pinpoint the source of this infection, we're aware that one of the cases had checked in to the Craigieburn Central shopping centre on 23 May," Professor Cheng said.
"We're not sure if either of them might have been in the shopping centre or at exposure sites close by."
There have been nine cases linked to Craigieburn Central shopping centre.
The first case, a man in his 80s, was tested on Tuesday after becoming symptomatic the day earlier. He returned a positive test on Wednesday along with his other household members.
It comes as state health authorities prepare to interview an infected Victorian couple who prompted COVID scares in Queensland and NSW.
The woman left Melbourne with her husband on 1 June, when the city was in lockdown, and tested positive at the end of a road trip through NSW and into Queensland
Her husband has now tested positive as well. No other cases have emerged in the community in Queensland.
"I think it is important to note that if they were relocating it is not a breach of directions here in Victoria but we just don't know," Mr Merlino said.
Separately, three people were caught flying into New Zealand last week, after leaving Melbourne during the lockdown and trying to enter the country via Sydney.
The trio, understood to be a family who planned to attend a funeral, are now in quarantine after they were caught on arrival in Auckland.
There are 78 active cases across Victoria, down five from Wednesday.
Some 23,679 Victorians were tested on Wednesday and 20,784 received a vaccine dose at state-run sites.
