In a court filing on Saturday, lawyers for Novak Djokovic said the tennis star had tested positive for the coronavirus in mid-December, and that the Australian government had erred this week in cancelling his visa over a vaccine requirement.

Djokovic, who hopes to defend his men’s singles title at the Australian Open this month, was denied permission to enter the country on Thursday after arriving at a Melbourne airport. The border authorities said they cancelled his visa because he had not provided evidence to justify being exempted from Australia’s requirement that arrivals be vaccinated against the coronavirus.

In the filing on Saturday, Djokovic’s lawyers said he had been granted a vaccine exemption by Tennis Australia because of a positive December 16 coronavirus test result, and because 14 days later, he had not had a fever or respiratory symptoms in 72 hours.

This, the lawyers said, was followed by a document Djokovic received on January 1 from the Department of Home Affairs, telling him his responses indicated that he met “the requirements for a quarantine-free arrival into Australia”.

The federal court has ordered the home affairs department to file its response by Sunday. The Australian Open is scheduled to begin on January 17.

The conditions of the exemption were consistent with the recommendations of Australia’s immunisation advisory body, the lawyers argued. Given these circumstances, among others, “Mr. Djokovic understood that he was entitled to enter Australia,” the filing read.

Djokovic, a vaccine sceptic, is in quarantine at a hotel in Melbourne as he awaits a hearing, scheduled for Monday, on his appeal of the government’s decision to revoke his visa.

He announced in June 2020 that he and his wife had tested positive for the coronavirus, but his December infection had not previously been disclosed.

Djokovic’s lawyers argue that the Australian authorities, in cancelling his visa, “radically and fundamentally” misconstrued or misapplied advice from Australia’s immunisation advisory body about whether a coronavirus infection within the past six months should exempt him from the vaccination requirement.