Three days after South Australia announced the reopening of their border, Victoria is not ruling out closing it again.
In a development that would have been unthinkable only a few weeks ago, Victoria has joined several other states in declaring SA a coronavirus hotspot because of an outbreak in Adelaide's northern suburbs.
Victoria has now gone 17 days without any virus deaths or new cases, a far cry from the second wave that made the state the national pariah.
Last Friday, SA announced it would reopen the Victoria border on December 1.
Now SA is reeling from an outbreak that has grown to 17 cases and Premier Daniel Andrews offered his support, while stressing that Victoria will stay vigilant.
"We've never closed our border. I've never criticised others for closing theirs, they've done what I would've done if the circumstances were different," he said.
"So I can't take it off the table. I've got confidence that (SA Premier) Steven Marshall will get on top of this.
"I want a situation where every border in the country is open by Christmas."
Victorian health department officials are now meeting all SA arrivals at Melbourne airport to check for symptoms and take temperatures.
Deputy Chief Health Officer Allen Cheng said travellers would be asked where they've been, and if from an identified "area of risk", requested to take a test and isolate.
"If they refuse to get tested they will be treated as a close contact and be asked to self-isolate for 14 days," Dr Cheng said.
Also on Monday, Melbourne City Council cancelled its traditional New Year's Eve fireworks in favour of a two-day dining festival that will be more low-key and COVID-safe.
"We just can't have crowds that big. That's sad," the premier said.
"Stay safe, stay open - that means making some very difficult choices and I fully support the decision."
He also blasted people involved in a St Kilda street party that breached virus rules.
Police broke up the party, which involved about 100 people.
"The people involved in that sort of activity, they know it's not the right thing to do," he said, adding the behaviour was "fundamentally selfish".
Meanwhile, Victoria's coronavirus test numbers are dropping off as its streak of no coronavirus deaths or new cases extends to 17 days.
While there are only three active cases in Victoria on Monday, tests in the previous 24 hours were down to 6695.
The government and health authorities are urging the public to be tested for even mild symptoms so they can pick up cases quickly.
Prime Minister Scott Morrison visited Melbourne on Monday for the first time since February and he was due to meet with the premier in the evening.
In a 3AW interview on Monday, Mr Morrison praised Victoria's contact tracing system - a bone of contention in the past between the two governments - saying it was "chalk and cheese, night and day" to the state's system earlier this year.
Mr Andrews was asked what his relationship was like with the federal government.
"Are we best mates? I don't know about that, but we work well together," he said.
Victoria's virus death toll stands at 819, with the national figure 907.