The nine-time Open champion was scheduled to arrive in Melbourne on Wednesday to defend his title and chase a record-setting 21st grand slam title.

He is one of only a "handful" of exemptions granted among 26 applications from players and their support staff.

The world No.1 will avoid 14 days quarantine upon arrival, with visitors to Australia who have medical exemptions treated the same as vaccinated arrivals, so he will be ready to play from day one on January 17.

Djokovic also won't face any extra testing procedures during the tournament.

But as Djokovic flew to Australia, the federal government threw a potential curveball.

Prime Minister Scott Morrison said Djokovic must prove he has a genuine medical exemption when he arrives.

"We await his presentation and what evidence he provides us to support that," the prime minister told a Wednesday media conference.

"If that evidence is insufficient, then he won't be treated any different to anyone else and he'll be on the next plane home.

"There should be no special rules for Novak Djokovic at all. None whatsoever."

Tiley insists the Serbian superstar didn't receive any special treatment and says Djokovic was anonymously assessed by two separate independent panels of medical experts.

He says Djokovic met the strict guidelines set by the federal government advisory group ATAGI (Australian Technical Advisory Group on Immunisation).

"If I want to come as an international visitor and I'm not vaccinated, and I meet those guidelines ... then I'm able to come in as an unvaccinated individual, so it's not just Novak," Tiley said on Wednesday.

"He went through that process and it's a completely legitimate application and process."

But Tiley empathised with the anger felt by the public given the vaccine mandates within Australia and multiple lockdowns in Victoria.

"The process has been clear and we completely understand and empathise that some would have been upset by the fact that Novak Djokovic has come in because of his statements around vaccination in the past couple of years," Tiley said.

Tiley added he wasn't privy to the medical condition that allowed Djokovic to receive the exemption.

While Djokovic was infected by COVID-19 in 2020, a positive COVID-19 test within the past six months is one possibility.

Djokovic announced his exemption via social media, however TA wouldn't release the exact number or details on other successful applicants citing privacy reasons.

Outspoken anti-vaxxing American Tennys Sandgren, a two-time Open quarter-finalist, didn't apply for an exemption because he didn't meet the criteria.

But he took to Twitter to wish Djokovic well: "Hope he wins the whole thing," Sandgren tweeted.

Russian world No.195 Natalia Vikhlyantseva can feel harshly treated, with her vaccination Sputnik V not recognised by Australian authorities and leaving her unable to play.

Djokovic isn't required to make his exemption reason public and, given he refused to disclose his vaccination status last year on the grounds of privacy, it seems unlikely he will share the information.

Aware of the community outrage, Tiley said it would be "helpful" if the 34-year-old did.

"We would love ... Novak to talk about it and help us with it, but ultimately it's going to be up to him," the tournament director said.

"We aren't in a position, even legally, to disclose other people's medical information."

As well as the widespread fury, many have expressed surprise that an elite athlete with 20 grand slam titles would need a medical exemption.

Former Australian Open chief Paul McNamee posed the question last month: "Why would he apply for one? He is the healthiest guy in the world."

But AFL great turned sports commentator Kevin Bartlett best captured the general sentiment of Australians on Wednesday.

"Novak Djokovic is the greatest tennis player ever," Bartlett tweeted.

"Forget Laver, Agassi, Federer, Sampras, Nadal, McEnroe, Connors and Borg for Novak has won 20 grand slams and 87 titles and a billion dollars without us knowing he had a debilitating medical problem.

"We have been taken for fools."

Australian Associated Press