Victorian Premier Daniel Andrews has announced on Sunday the state's lockdown will extend for another two weeks beyond the original September 13 deadline.
The state entered level 4 lockdown in August for six weeks, and it will now be extended to September 27.
However there will be some changes. From next Sunday, the curfew will be expanded to 9pm, not 8pm, and exercise will be allowed for up to two hours a day.
"I apologise for the circumstances we find ourselves in," Andrews said. "I apologise for the reality we find ourselves in. But we can't change that. We can't simply wish that away.
"I am 100 percent accountable for where we find ourselves, but equally, I'm accountable for getting us to the other side of this. And, pretending it's over, because we wanted to be, that is not something I will do."
The lockdown extension comes a day after the government released modelling by experts at Melbourne University and the University of New England on whether case numbers would still continue to drop once restrictions ease.
Victoria's daily average case this week has been 84 - and "it is unlikely we will have aggressively suppressed the virus by mid-September," the report said.
The modelling predicted cases were now reducing by 50 percent every 18 days. Based on current rates, there will still be an average of 60 daily cases by mid-September.
At this rate, Victoria's daily cases wouldn't be below 20 until late October.
Victoria has recorded 63 new coronavirus cases in the past 24 hours and five more deaths.
This brings the state's total deaths to 666 and the country's death toll to 753.