MELBOURNE, Australia — Novak Djokovic was reported to be back in immigration detention Saturday after his legal challenge to avoid being deported from Australia for being unvaccinated for COVID-19 was moved to a higher court.

A Federal Court hearing has been scheduled for Sunday, a day before the men’s No. 1-ranked tennis player and nine-time Australian Open champion was due to begin his title defense at the first Grand Slam tennis tournament of the year.

Police closed down a lane behind the building where Djokovic’s lawyers are based and two vehicles exited the building mid-afternoon local time on Saturday. In television footage, Djokovic could be seen wearing a face mask in the back of a vehicle near an immigration detention hotel.

The Australian Associated Press reported that Djokovic was back in detention. He spent four nights confined to a hotel near downtown Melbourne before being released last Monday when he won a court challenge on procedural grounds against his first visa cancellation.

Immigration Minister Alex Hawke on Friday blocked the 34-year-old Serb’s visa, which was originally revoked when he landed at a Melbourne airport on Jan. 5.

Deportation from Australia can lead to a three-year ban on returning to the country, although that may be waived, depending on the circumstances.

Djokovic has acknowledged that his travel declaration was incorrect because it failed to indicate that he had been in multiple countries over the two weeks before his arrival in Australia.

But the incorrect travel information is not why Hawke decided that deporting Djokovic was in the public interest.

His lawyers filed documents in court on Saturday that revealed Hawke had stated that “Djokovic is perceived by some as a talisman of a community of anti-vaccination sentiment.”

Australia is one of the most highly vaccinated populations in the world, with 89% of people aged 16 and older fully inoculated against COVID-19.

But the minister said that Djokovic’s presence in Australia may be a risk to the health and “good order” of the Australian public. His presence “may be counterproductive to efforts at vaccination by others in Australia,” the minister said.

The Health Department advised that Djokovic was a “low” risk of transmitting COVID-19 and a “very low” risk of transmitting the disease at the Australian Open.

The minister cited comments Djokovic made in April 2020, before a COVID-19 vaccine was available, that he was “opposed to vaccination.”

Djokovic had “previously stated he wouldn’t want to be forced by someone to take a vaccine” to compete in tournaments.

The evidence “makes it clear that he has publicly expressed anti-vaccination sentiment,” the minister wrote in his reasons for canceling Djokovic’s visa.

Djokovic’s lawyers argue that the minister had cited no evidence that Djokovic’s presence in Australia may “foster anti-vaccination sentiment.”

Djokovic will be allowed out of hotel detention on Sunday to visit his lawyers’ offices for the video court hearing.

On Saturday, Justice David O’Callaghan suggested a full bench rather than a single judge hear the case on Sunday. A full bench is three or five judges.

A full bench would mean any verdict would be less likely to be appealed. The only avenue of appeal would be the High Court and there would be no guarantee that that court would even agree to hear such an appeal.

Djokovic’s lawyer Paul Holdenson opted for a full bench while Hawke’s lawyer Stephen Lloyd preferred a single judge.

Legal observers suspect Lloyd wants to keep the option open of another Federal Court appeal because he thinks the minister can mount a stronger case without the rush to reach a verdict before Monday.

Chief Justice James Allsop will decide how many judges hear the case.

The case on Saturday was elevated from the Federal Circuit and Family Court to the Federal Court. But the number of judges who will hear the case starting at 9:30 a.m. local time (5:30 p.m. ET) on Sunday had yet to be determined.

Djokovic has won the past three Australian Opens, part of his overall Grand Slam haul of 20 championships. He is tied with Rafael Nadal and Roger Federer for the most by a man in history.

In a post on social media Wednesday that constituted his most extensive public comments yet on the episode, Djokovic blamed his agent for checking the wrong box on the form, calling it “a human error and certainly not deliberate.”

In that same post, Djokovic said he went ahead with an interview and a photo shoot with a French newspaper in Serbia despite knowing he had tested positive for COVID-19 two days earlier. Djokovic has been attempting to use what he says was a positive test taken on Dec. 16 to justify a medical exemption that would allow him to skirt the vaccine requirement on the grounds that he already had COVID-19.

In canceling Djokovic’ visa, Hawke said that Prime Minister Scott Morrison’s government “is firmly committed to protecting Australia’s borders, particularly in relation to the COVID-19 pandemic.”

Morrison himself welcomed Djokovic’s pending deportation. The episode has touched a nerve in Australia, and particularly in Victoria state, where locals went through hundreds of days of lockdowns during the worst of the pandemic.

Australia faces a massive surge in virus cases driven by the highly transmissible omicron variant. On Friday, the nation reported 130,000 new cases, including nearly 35,000 in Victoria state. Although many infected people aren’t getting as sick as they did in previous outbreaks, the surge is still putting severe strain on the health system, with more than 4,400 people hospitalized. It has also disrupted workplaces and supply chains.

“This pandemic has been incredibly difficult for every Australian, but we have stuck together and saved lives and livelihoods. … Australians have made many sacrifices during this pandemic, and they rightly expect the result of those sacrifices to be protected,” Morrison said Friday. “This is what the Minister is doing in taking this action today.”

Djokovic’s supporters in Serbia have been dismayed by the visa cancellations.

Everyone at the Australian Open — including players, their support teams and spectators — is required to be vaccinated. Djokovic is not inoculated.

His exemption was approved by the Victoria state government and Tennis Australia, apparently allowing him to obtain a visa to travel. But the Australian Border Force rejected the exemption and canceled his visa when he landed in the country.

Djokovic spent four nights in an immigration detention hotel before a judge overturned that decision. That ruling allowed him to move freely around Australia and he has been practicing at Melbourne Park daily.

“It’s not a good situation for anyone,” said Andy Murray, a three-time Grand Slam champion and five-time runner-up at the Australian Open. “It just seems like it’s dragged on for quite a long time now.”

According to Grand Slam rules, if Djokovic is forced to pull out of the tournament before the order of play for Day 1 is announced, No. 5 seed Andrey Rublev would move into Djokovic’s spot in the bracket.

If Djokovic withdraws from the tournament after Monday’s schedule is released, he would be replaced in the field by what’s known as a “lucky loser” — a player who loses in the qualifying tournament but gets into the main draw because of another player’s exit before competition has started.

And if Djokovic plays in a match — or more — and then is told he can no longer participate in the tournament, his next opponent would simply advance to the following round and there would be no replacement.