Several Australian Open COVID cases to be reclassified as 'shedding'

Other players and their support staff are allowed to train at Melbourne Park, the National Tennis Centre and Albert Reserve courts for up to five hours each day.

With some cases due to be reclassified, hard quarantine conditions could ease for several players and support staff.

"If you've got say 30 people who are deemed a close contact because they've been on a plane with a case, and the case is no longer an active case, but a historic shedding, well then, that would release those people from that hard lockdown," Mr Andrews said.

Some of the 320-odd players in Melbourne, who are currently allowed to train, missed their session on Monday due to delays that prompted an apology from Tennis Australia.

Four coronavirus cases – one of whom Victoria's Chief Health Officer Brett Sutton said was believed to be a player – linked to the Australian Open were confirmed by officials on Monday. A member of the air crew on one of 17 flights chartered by tournament organisers also tested positive to the virus.

Infectious disease experts have warned more cases are "very likely" in the coming days as COVID-19 could still be incubating in some of the 1200 tennis players and officials.

More than 15,500 Victorians were tested for the virus in the 24 hours before midnight on Monday.

Meanwhile, travel restrictions remain in place for large swathes of regional NSW that have not recorded a coronavirus case for months despite an Andrews government move to relax the hard border closure for people in some parts of Sydney.

Parts of Sydney's "red zone" were downgraded at 6pm on Monday to orange and all border towns are now green zones, paving the way for some Victorians now stranded in NSW to return home without special exemptions.

Anyone in an orange zone can travel home but must quarantine until receiving a negative test result, while anyone in a red zone cannot enter Victoria.

A western Sydney mayor has said his residents are being treated as "second-class citizens" by Mr Andrews because they’re not able to travel to the southern state under the harsh border restrictions.

Fairfield City mayor Frank Carbone said he cannot see why his local government area is still being treated as a "red zone" given it has not had a new case of COVID-19 for almost 90 days.

"It is quite clear that it seems that if you hold a tennis racket these days, it has a lot more power than having an Australian passport," Mr Carbone told the Today show on Tuesday morning.

"I don't want western Sydney to be treated as second-class citizens and I will always stand up for my community because I'm very proud of what Fairfield has achieved. We've had the virus before and overcome it."

Mr Andrews said there was a "real chance" that the current status of Brisbane could change from orange to green in the near future.

"If they stay on the path they're on now, then hopefully we can have them green and indeed hopefully we can have New South Wales green very soon as well," the Premier said.

But he said daily analysis of the 10 remaining red zones within Greater Sydney was a priority "so everybody who needs to come home can come home".

"Then we can we can talk about what the green status of different parts of the country [is]," Mr Andrews said.

Tuesday marks exactly a year since Australian health authorities went public with their concerns about a mystery illness emerging in China that, unbeknown to them at the time, would claim 909 Australian lives.