Victoria has recorded no new local cases of coronavirus, with most close contacts of an infected hotel security guard testing negative and two results still pending.
The Department of Health on Friday confirmed no new cases of community transmission following 14,612 tests in 24 hours.
There were three new cases among returned travellers in hotel quarantine, bringing the total number of active infections in the state to 24.
The 26-year-old man, from Noble Park in Melbourne's southeast, tested positive to COVID-19 on Wednesday, five days after completing his last shift at the Grand Hyatt Hotel.
The hotel was one of three being used to quarantine Australian Open tennis players, officials and support staff.
It is still unknown if the man is carrying a more-virulent international variant of the virus, with the results of genomic testing expected on Friday.
Late on Thursday, the health department confirmed it had identified 17 of the quarantine worker's close social and household contacts.
Fifteen of those have tested negative so far, including two of his household contacts.
A further 600 casual contacts have also been told to isolate and get tested, as have 507 tennis players, officials and support staff.
Tennis Australia boss Craig Tiley said 495 of those had returned negative results, with just 12 still pending after being tested late on Thursday.
"It's a timing thing," he told Melbourne radio station 3AW on Friday.
"Hopefully in the next few hours we get the positive outcome that all are negative."
Melbourne Park lead-up matches will resume on Friday following Thursday's suspension.
Mr Tiley said the Open would go ahead as planned from next Monday and there has been no change to daily crowd arrangements, initially capped at 25,000 to 30,000.
Premier Daniel Andrews said the man had worked at the Grand Hyatt hotel and a review of security footage showed he was a "model employee" who correctly followed all safety procedures.
Deputy Chief Health Officer Allen Cheng said it was likely the man contracted the virus from a positive case in the quarantine hotel.
However his case was not picked up as part of the state's daily testing regime of hotel quarantine staff as he last worked at the hotel on 29 January.
Instead, he went to be tested of his own accord after developing symptoms.
"We are making sure they are tested on their days off," Mr Cheng said.
"There will be a testing program for people that finish work."
Meanwhile, the scare has prompted a number of states to introduce new testing requirements for people travelling from Victoria, including NSW, SA, Tasmania, Queensland and WA.
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