The new category of positive cases will be introduced from Friday, imposing the same rights and obligations as anyone who tests positive with a PCR test.

The tweak to the rules comes as Victoria reported 21,997 new cases on Thursday, one-third of the 64,000 results recorded.

"In the eyes of the health department, you have COVID," acting chief health officer Ben Cowie said of those receiving a positive result from a rapid antigen test.

Probable cases must immediately isolate for seven days, notify their contacts and report to the health department over the phone, or with an online form expected to go live on Friday.

Professor Cowie said those people were being discouraged from confirming the result with a PCR test unless they have no symptoms and are not a contact of a positive case - those least likely to have COVID.

Health Minister Martin Foley said probable cases would receive the same clinical and financial support as PCR confirmed cases.

"The goal is to bring it as close to, if not exactly the same as, the supports that the PCR reporting system has and make sure that increasingly, the rapid antigen testing is the key part of our testing," he said.

Probable cases will be reported alongside the daily figures.

Restrictions are also being reintroduced in an effort to limit the spread.

Density limits of one person per two square metres will be brought in for indoor hospitality and entertainment venues from Friday. Cinemas and theatres, where people are seated and masked, will be exempt.

Mr Foley, meanwhile, distanced the state from the "messy" process around No.1 tennis player Novak Djokovic's entry into the country for the Australian Open.

"The Commonwealth lets you into the country, Tennis Australia in partnership with the state lets you into the tournament," he said.

"Someone issued Novak Djokovic a visa. It wasn't the Victorian government."

Djokovic's visa was cancelled by the Australian government on Thursday morning before he was moved to a Melbourne quarantine facility.

He has since launched a federal court challenge of the decision and will not be deported until at least Monday, pending the outcome of a 10am hearing.

Opposition Leader Matthew Guy said the saga was "shameful" and had done reputational damage to Melbourne.

"Surely the Victorian government liaised with Border Force before they sent an invitation to Novak Djokovic to come to the Australian Open," he said.

VICTORIA'S LATEST COVID-19 FIGURES:

* Active cases: 61,120

* Hospital cases: 631, up 40

* Hospital cases seven-day average: 537

* Active cases in ICU: 51

* Cleared cases in ICU: 49

* Cases on a ventilator: 22

Australian Associated Press