Three of Victoria's four new cases are among Australian Open players and staff, with two previously reported infections ruled viral shedding.
Victoria has recorded no new locally acquired cases of coronavirus for a 13th consecutive day, although more infections are among players and staff who have flown in for the Australian Open.
Premier Daniel Andrews on Tuesday confirmed there are four new cases of COVID-19 in hotel quarantine, three of which are linked to the contingent in town for the grand slam.
Two are players and another is a non-playing participant, Victoria's Chief Health Officer Brett Sutton said on Tuesday afternoon.
One is a woman in her 20s and the other two are men in their 30s.
The fourth infection was detected in hotel quarantine among a female returned traveller in her 30s.
It brings the number of active infections in the state to 34, an increase of one.
Some 72 players - almost a fifth of those taking part in the Australian Open - have been forced into strict quarantine over positive tests on three charter flights to Melbourne from Abu Dhabi, Doha and Los Angeles.
Two previously reported cases have been deemed viral shedding, lowering the tournament's total cases to seven.
But Professor Sutton said affected players were still unable to leave their rooms for training, unlike others who arrived on flights with a clean bill of health.
"This does not change broader assessment of the player group in hotel quarantine," he said.
"As yet, none of the three affected flights have been cleared as a result of the two reclassified cases."
Mr Andrews had earlier indicated players could be free to practise if a case was ruled non-infectious shedding.
"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 that would release those people from that hard lockdown," he told reporters.
Prof Sutton is warning the virus could still be incubating in some of the 1,200 people who have arrived in Melbourne for the Open since Thursday.
"People may still turn positive, obviously the last exposure was when they last left their country of origin or indeed on a flight where there was a case," he said.
"So there might be some more positives in coming days but that that will take place over time."
Meanwhile, 25 of Sydney's 35 local government areas were downgraded from "red" to "orange" zones at 6pm on Monday as part of Victoria's "traffic light" permit system.
The Blue Mountains and Wollongong also moved from red to orange, while 16 local government areas along the NSW-Victoria border changed from orange to green, permitting unrestricted entry.
People travelling from an orange zone still need to apply for a permit online and get tested within 72 hours of their arrival in Victoria, isolating until they receive a negative result.
In the 24 hours to midday on Tuesday, 25,956 permit applications were processed.
It follows the downgrading of Greater Brisbane from red to orange at the weekend.
Sydney local government areas Blacktown, Burwood, Canada Bay, Canterbury-Bankstown, Cumberland, Fairfield, Inner West, Liverpool, Parramatta and Strathfield remain red zones for now.
The 10 areas were all linked to Sydney's Berala cluster, which totals 35 cases.
People in Australia must stay at least 1.5 metres away from others. Check your jurisdiction's restrictions on gathering limits.
If you are experiencing cold or flu symptoms, stay home and arrange a test by calling your doctor or contact the Coronavirus Health Information Hotline on 1800 020 080.
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