Nine-time and reigning Australian Open champion Djokovic has refused to say if he's vaccinated - or if he intends to get vaccinated.

"We'll see. We'll have to wait and see," Djokovic said of the Australian Open after losing to Alexander Zverev in the semi-finals of the ATP Finals in Turin on Saturday.

"I haven't been talking to them, to be honest," Djokovic added. "I was just waiting to hear what the news is going to be and now that I know we'll just have to wait and see."

There is a lot riding on it for Djokovic.

If he does go to Melbourne, he can attempt to break a tie with Roger Federer and Rafael Nadal and win a record 21st grand slam singles title.

The Victorian state government had previously said only vaccinated people will be be allowed into the Australian Open, which runs from January 17-30, and Tiley reiterated that on Saturday.

"Everyone on site, the fans, all the staff, the players, will need to be vaccinated," Tiley said at the tournament's launch.

"There's been a lot of speculation about Novak's position, he's said it's a private matter.

"We would love to see Novak here, but he knows he needs to be vaccinated in order to play. He's always said that the Australian Open is the event that puts the wind in his sails."

The third-ranked Zverev was asked if Djokovic's handling of the vaccine issue should be better respected.

"This is a very tough one because it's very political," Zverev said. "At the end of the day I don't know his criteria.

"But we are visiting another country. This is not about tennis. This is about the virus that is going on, right? ... At the end of the day, the country is allowing us to enter. We need to follow the rules and follow the guidelines," Zverev said.

Zverev said that while it would be "easier to win the tournament" if Djokovic doesn't play, "he's No.1 in the world so he should be there.

"Hopefully," the German concluded, "the Australian government will make an exemption or whatever it is that they can do for him to be able to participate there."

Djokovic is scheduled to play for Serbia at the Davis Cup finals next week in Austria, which has just announced a national lockdown and a plan to mandate vaccinations as coronavirus infections hit a record high.

People visiting Austria for work during the lockdown have to pre-register and show a negative PCR test if they are not vaccinated or recently recovered from COVID-19.

Djokovic and his wife tested positive for the coronavirus last year after he played in a series of exhibition matches that he organised in Serbia and Croatia without social distancing amid the pandemic.

Australian Associated Press