MELBOURNE: Australia cancelled Novak Djokovic's visa for a second time on Friday saying the world number one tennis champion who has not been vaccinated for COVID-19 may pose a health risk, effectively ending his bid for a record 21st Grand Slam title at the Australian Open.

Immigration Minister Alex Hawke used discretionary powers to again cancel Djokovic's visa, after a court quashed an earlier revocation and released him from immigration detention on Monday.

"Today I exercised my power under section 133C(3) of the Migration Act to cancel the visa held by Mr Novak Djokovic on health and good order grounds, on the basis that it was in the public interest to do so," Hawke said in a statement.

Under the section of the Migration Act used to cancel the visa, Djokovic would not be able to secure a visa to Australia for three years, except in compelling circumstances that affect Australia's interest.

The decision to again cancel his visa over COVID-19 entry regulations raises the prospect of a possible second court battle by the Serbian tennis star to be allowed to stay and play in the Open starting Monday.

The controversy has assumed an importance that goes beyond tennis: it has intensified a global debate over the rights of the unvaccinated and become a tricky political issue for Prime Minister Scott Morrison as he campaigns for an election that is due by May.

While Morrison's government has won support at home for its tough stance on border security during the pandemic, it has not escaped criticism over the botched handling of Djokovic's visa.

Djokovic, 34, the Australian Open defending champion, was included in Thursday's draw as top seed and was due to face fellow Serb Miomir Kecmanovic for his opening match, probably on Monday or Tuesday.

A relaxed looking Djokovic practised his serves and returns with his entourage on an empty court at Melbourne Park earlier on Friday, occasionally resting in a chair to wipe sweat from his face.

Djokovic, a vaccine sceptic, fuelled widespread anger in Australia when he announced last week he was heading to Melbourne for the Australian Open with a medical exemption to requirements for visitors to be inoculated against COVID-19.

On arrival, Australian Border Force decided his exemption was invalid and put him in an immigration detention hotel alongside asylum-seekers for several days.

The government "is firmly committed to protecting Australia's borders, particularly in relation to the COVID-19 pandemic", Hawke said.

He said he had "carefully considered" information from Djokovic, the Department of Home Affairs and the Australian Border Force.

Australia has endured some of the world's longest lockdowns, has a 90 pct vaccination rate among adults, and has seen a runaway Omicron outbreak bring nearly a million cases in the last two weeks.


'CHEEKY'

Greek world number four Stefanos Tsitsipas had said Djokovic was "playing by his own rules" and making vaccinated players "look like fools".

"No-one really thought they could come to Australia unvaccinated and not having to follow the protocols ... it takes a lot of daring to do and putting the grand slam at risk, which I don't think many players would do," Tsitsipas said in an interview with India's WION news channel.

"The stats say 98 per cent of players have been vaccinated and did what they had to do in order to come and perform and play in Australia," he said.

An online poll by the News Corp media group found that 83 pct favoured the government trying to deport the tennis star.

"Absolutely, he should go. He hasn't done the right thing and is being a bit cheeky about it," said Venus Virgin Tomarz, 45, who lives in Melbourne.

"To be honest, it's political. But if what the media are saying is true - that he didn't come with the right paperwork - he should be treated just like everyone else," said Jacob Coluccio, 25, who also lives in Melbourne.

"It should never have come to this," said opposition Labor leader Anthony Albanese.

"They have never answered the question of how is it that that visa was granted in the first place if he wasn't eligible because he wasn't fully vaccinated."

Djokovic's cause was not helped by a wrong entry declaration, where a box was ticked stating he had not travelled abroad in the two weeks before leaving for Australia.

In fact, he had travelled between Spain and Serbia.

Djokovic blamed the error on his agent and acknowledged he also should not have done an interview and photoshoot for a French newspaper on Dec. 18 while infected with COVID-19.