Spectators will not be allowed at the Australian Open for the next five days after Premier Daniel Andrews announced a snap lockdown for Victoria on Friday.
A COVID-19 outbreak connected to the Holiday Inn at Melbourne Airport has grown to 13 cases, forcing Andrews to put the city back into a five-day lockdown from midnight on Friday.
'QUITE HEATED': John Tomic in 'clash' with Sam Groth
That means fans will be locked out of Melbourne Park, where the Australian Open is being held, from Saturday until Wednesday.
Spectators will still be allowed to attend matches on Friday, including Nick Kyrgios' showdown with World No.3 Dominic Thiem.
“Venues hosting professional sporting competitions can open, with essential staff attending to ensure the safe running of the event,” Mr Andrews said.
“(Sporting events) will function essentially as a workplace. But they will not function as an entertainment event."
Players, officials and support staff will be subject to the same stage four restrictions as the rest of the state.
Mr Andrews said the UK strain of the virus is "so hyper-infectious and moves so fast that it is presenting a very real challenge" for authorities.
"It is the advice to me that we must assume that there are further cases in the community than we have positive results for, and that it is moving at a velocity that has not been seen anywhere in our country over the course of these last 12 months," he said.
Speaking earlier on Friday, Prime Minister Scott Morrison noted hotel quarantine workers have also contracted the virus in Adelaide, Brisbane, Perth and Sydney, sparking short lockdowns in those cities.
"We have dealt with these before, got on top of them before," Mr Morrison told reporters.
"A proportionate response that enables the (contact) tracers and others, to be able to get on top of it and get the same successful result we have seen in other states - that can and will be achieved here."
Mr Morrison said he understood Melburnians did not want to endure another long lockdown.
"As other states have demonstrated, you can get on top of this pretty quickly, and I have reason for confidence that they can do the same thing by following that same process," he said.
Victoria recorded five new COVID-19 cases on Friday, all of which are connected to the Holiday Inn outbreak.
The new cases include a female assistant manager and four close contacts of people who earlier tested positive to COVID-19.
One of the five is believed to have had some contact with Camberwell Grammar School.
"We believe there will be some additional exposure sites emerging from some of these cases," Victoria's COVID-19 Testing Commander Jeroen Weimar said on Thursday.
Fans banned from Australian Open
Up to 30,000 fans have been allowed at Melbourne Park every day this week, provided they practice good social-distancing.
Victoria's Minister for Sport Martin Pakula had previously announced that a daily crowd capacity of 30,000 for the first eight days and then 25,000 per day from the start of the quarter-finals would be allowed.
"Over the 14 days, it means we will have up to 390,000 people here at Melbourne Park, about 50 per cent of the average over the past few years," he said.
"Rod Laver Arena will have incredible atmosphere, not that different to the atmosphere we’ve seen at all the Opens in the years past.
"It will not be the same … but it will be the most significant international event with crowds that the world has seen in many, many months."
Click here to sign up to our newsletter for all the latest and breaking stories from Australia and around the world.