The filing ahead of a court hearing on Monday was in defence of the government's decision to bar entry to the world number one player over his COVID-19 vaccination status.

Djokovic's legal team said he had the necessary permissions to enter Australia, including an assessment from the Department of Home Affairs that responses on his travel declaration form indicated he met the conditions for quarantine-free arrival. The government disputed this.

"This is because there is no such thing as an assurance of entry by a non-citizen into Australia. Rather, there are criteria and conditions for entry, and reasons for refusal or cancellation of a visa," the government's filing said.

It said the department's email was not an assurance "that his so-called 'medical exemption' would be accepted", and his responses could be questioned and verified on his arrival.

The government also challenged Djokovic's claim for a medical exemption on the basis he had contracted COVID-19 and had recovered two weeks later.

"There is no suggestion that the applicant had "acute major medical illness" in December 2021. All he has said is that he tested positive for COVID-19. This is not the same," the filing said.

Australia says its health department notified tournament organising body Tennis Australia in November that a recent COVID-19 infection was not necessarily grounds for exemption in the country, as it is elsewhere. Djokovic's lawsuit says the Department of Home Affairs wrote to him this month to say he had satisfied the requirements to enter the country.

Earlier on Sunday, the government's bid to get the visa appeal hearing delayed from Monday to Wednesday was rejected by Judge Anthony Kelly. However, the judge left the government with the option of making another application to delay on Monday.

Djokovic's lawyers have claimed the Serb was granted a vaccine exemption to enter Australia because he contracted Covid-19 on December 16.

The world number one has been detained at an immigration facility in Melbourne since Thursday morning after his visa was cancelled.

According to his legal team, Djokovic - who is hoping to win his 21st Grand Slam title - was also provided with a letter from the Chief Medical Officer of Tennis Australia recording he had a medical exemption from Covid vaccination.

It is claimed that the exemption certificate was "provided by an Independent Expert Medical Review panel commissioned by Tennis Australia", and that "the decision of that panel had been reviewed and endorsed by an independent Medical Exemptions Review Panel of the Victorian State Government".

Djokovic's lawyers added that he was granted an "Australian Travel Declaration" because he was told by the authorities that [he met] the requirements for a quarantine-free arrival into Australia".

A vocal opponent of vaccine mandates, Djokovic had declined to reveal his vaccination status or reason for seeking a medical exemption from Australia's vaccine rules.

The Melbourne drama has rocked world tennis, caused tensions between Serbia and Australia and become a flashpoint for opponents of vaccine mandates around the world.

Writing on Instagram on Friday, Djokovic thanked his fans for their support. He said: "Thank you to people around the world for your continuous support. I can feel it and it is greatly appreciated. Thank you to my family, Serbia and all good people across the world who are sending me support. Thanks to dear God for health."

• Djokovic's Aussie Open debacle: What's happened?
• Djokovic 'had positive Covid test in Dec' | Second player leaves Aus

Djokovic's lawyers will have up to two hours to present their case from 10am on Monday (2300 GMT on Sunday), while the government department gets two hours to present its defence from 3pm (0400GMT), the Federal Circuit and Family Court ruled.

A Home Affairs spokesperson was not immediately available for comment about its legal defence.

Why was Djokovic in public after alleged positive test?

Novak Djokovic is facing fresh questions over why he was pictured in public on the day he claimed he tested positive for Covid-19.

In legal documents, Djokovic has claimed he tested positive on December 16, but the world number one attended an event on the same day at the Belgrade headquarters of the Serbian national post office, which was honouring him and his career with the release of a series of stamps.

Djokovic posted pictures from the event - in which he is seen maskless - on his Twitter account on December 17.

It is unclear if Djokovic knew he had Covid when he attended the event.

Murray: Djokovic saga not good for tennis

Addressing the situation publicly for the first time, Djokovic's long-time rival Andy Murray said on Sunday that he is concerned for the Serb and that his predicament is "really not good for tennis at all".

"I think everyone is shocked by it, to be honest," five-time Australian Open finalist Murray told reporters in Australia.

"I'm going to say two things on it just now. The first thing is that I hope that Novak is OK. I know him well, and I've always had a good relationship with him and I hope that he's OK.

"The second thing, it's really not good for tennis at all, and I don't think it's good for anyone involved. I think it's really bad."

Djokovic's Aussie Open debacle: What's happened?

Djokovic flew to Australia with a 'vaccine exemption' and arrived in Melbourne on Wednesday, but was ultimately denied entry into the country after nine hours at the airport.

The Serb's visa was one that did not allow for medical exemptions and was cancelled, after which he was moved to hotel quarantine as his team launched an appeal - this appeal has been adjourned until Monday morning at 10am local time (Sunday 11pm GMT).

The Australian Home Affairs department appealed for the hearing to be delayed until Wednesday, but their request was rejected on Sunday by Judge Anthony Kelly.

On Sunday, the govt filled documents in defence of their decision to deny Djokovic entry. "This is because there is no such thing as an assurance of entry by a non-citizen into Australia. Rather, there are criteria and conditions for entry, and reasons for refusal or cancellation of a visa," the government's filing said.