Earlier on Thursday,Djokovic’s father Srdjan Djokovic told a Serbian media outlet his son had been separated from his team overnight and taken to a room where he remained under armed guard. “Novak is currently in a room where no one can enter,” he told the B92.

In comments reported by Russian news agency Sputnik,Djokovic’s father said:“I have no idea what is happening,they are holding my son in captivity for five hours.”

“I have no idea what is happening,they are holding my son in captivity for five hours.”

Srdjan Djokovic

“This is a fight for the liberal world,this is not just a fight for Novak,but a fight for the whole world.”

Serbia’s President Aleksander Vucic said “the whole of Serbia” supported Djokovic. “Our authorities are taking all measures to stop the harassment of the best tennis player in the world in the shortest possible period,” Vucic posted to his Instagram account.

He said he had spoken to the tennis player on the phone this morning (AEDT). “In accordance with the norms of international public law,Serbia will fight for Novak Djokovic,for justice and truth. Otherwise,Novak is strong,as we all know him.”

A source close to Tennis Australia,speaking anonymously,said it appeared federal officials blocked Djokovic’s entry to avoid the potentially unpopular appearance of allowing him into the country with a medical exemption.

“I don’t know how the feds will[address the fact that] several tennis players are already in the country with the same exemption granted to Novak,” the source said.

“This looks to us like the feds are responding to the media by letting some players in but not the World No. 1.”

In a separate issue that complicated his arrival,acting Victorian Sports Minister Jaala Pulford said Border Force officials contacted the state government hours before Djokovic landed. The 20-time grand slam winner was attempting to enter the country on a visa that did not permit medical exemptions for being unvaccinated,a source briefed on the matter toldThe Ageand the Herald.

As a result,Ms Pulford said Border Force sought Victorian government support to facilitate Djokovic’s entry. The federal agency asked for the Andrews government’s support because Victoria partners with Tennis Australia in running the event that Djokovic sought his visa for. Victorian officials asked the federal authorities to put their request in writing and Ms Pulford said the request to sponsor Djokovic’s visa was rejected.

In a late-night tweet,Ms Pulford said the Victorian government would not be supporting Djokovic’s visa application.

However,on Thursday morning a spokeswoman for Border Force and Home Affairs Minister Karen Andrews rejected Ms Pulford’s claims.

Later on Thursday,Victorian Health Minister Martin Foley said Djokovic’s visa was not the state’s responsibility.

“Someone issued Novak Djokovic a visa and it wasn’t the Victorian government,” Mr Foley said. “What the Victorian government has done,what Tennis Australia has done,is acted within the law of the land.”

Mr Foley said health advice on Australian Open crowd numbers had been sought,although no changes had been made.

“I am confident that the Australian Open will continue and will go forward with a very strong crowd,” he said. “We managed to do that pretty successfully at the MCG and I’m confident we can do that at the Australian Open.”

Meanwhile,some Djokovic supporters gathered outside the international arrivals terminal at Melbourne Airport on Thursday,and then later outside the Park Hotel at Carlton.

At the airport,fan Krstomir Dusanovic played the accordion,while Slobodan Bendjo held a Serbian flag. “We’ve heard a lot of news these days and quite negative news. But we came here to bring some positive energy to that,” Mr Bendjo said.

Billy and Ziggy Misovic yelled,“Novak,Novak!” outside the Park Hotel. “Thank you Australia for locking him down like a refugee,like a criminal,” Ziggy Misovic said,holding a flag for Belgrade,Djokovic’s hometown.

Refugee advocates also gathered outside the hotel,holding placards that read “free the refugees” and “justice for refugees:one out,all out”,among others.

with Cassandra Morgan,Tammy Mills

The Morning Edition newsletter is our guide to the day’s most important and interesting stories,analysis and insights.Sign up here.