Authorities believe there are still undetected cases of coronavirus in Victoria, despite the state recording its fourth consecutive day of no new infections and no deaths.
The last time Victoria went four straight days of no new cases was in late February, with Chief Health Officer Brett Sutton hailing it as a Melbourne Cup day "quaddie".
At the time, the state had recorded less than 10 cases in total and there was no local transmission.
There are now 38 active coronavirus cases in Victoria, the lowest number of active cases since the government began recording them on March 29.
Victoria's Commander of Testing Jeroen Weimar said while the figures are positive, there is a "long road ahead" before the state can return to 'COVID-normal'.
"Today's a good day, the case numbers are very low, the weather is good," he told reporters in St Kilda on Tuesday.
"We're not over this by any means, we've got a long way to go to make sure we identify any remaining areas of transmission."
Mr Weimar said there are "absolutely" more undetected cases of COVID-19 in the community.
"They may be asymptomatic, they may be at a very low level, they may all be connected, they may not be connected," he said.
"It's our job to be really vigilant."
He encouraged anyone with a runny nose, sore throat or any other COVID-19 symptoms to get tested.
Some 12,841 Victorians were tested on Monday.
Health Minister Martin Foley confirmed Melbourne's latest mystery case is a Deer Park local who tested positive for the virus on October 29.
Authorities have been unable to link the case to a known outbreak.
It brings the tally of mystery cases in the fortnight to October 31 to two.
About 100 close contacts and secondary contacts of the Deer Park man are self-isolating.
Meanwhile, no additional cases have been linked to an outbreak in Melbourne's northern suburbs, which totals 42 people across 12 households and two schools.
Hundreds linked to the outbreak have been in self-isolation, with positive cases currently undergoing day 11 testing.
"That's going incredibly well," Mr Weirmar said.
"We have detected no new cases now over the last five to six days around the northern suburbs, so we are very much seeing the tail end of that particular outbreak."
He thanked the 40,000 people from the northern suburbs who have fronted up for testing since the outbreak emerged.
It came as Mr Foley urged Victorians heading outdoors to behave appropriately, as the state recorded its warmest Cup day since 1969.
Police were out in force at an anti-lockdown protest outside parliament house in Melbourne's CBD, as scenes turned ugly.
Over 400 people were arrested and 395 fines handed out for a range of offences.
A female senior sergeant was taken to hospital after suffering a broken arm during an arrest.
Police said they would also have a "highly visible presence" at beaches, parks and shopping precincts.
While Flemington Racecourse was closed to punters for the Cup's 160th running, pubs and bars were open to pick up the slack but limited to caps of 50 people outdoors and 20 indoors.
Only two adults plus dependants from one household were allowed over for a Cup day party, while thousands flocked to beaches in St Kilda, Brighton and Williamstown.
Mr Foley confirmed those heading to the beach would have to wear masks when they weren't in the water, but many flouted the order.
The state's virus death toll remains at 819 and the national figure at 907.