Novak Djokovic returned to the tennis court Monday for training, having won a legal battle to stay in Australia to play in the Australian Open after his exemption from strict coronavirus vaccine rules was questioned. But the government is still threatening to cancel his visa and deport him.

The unvaccinated tennis star was released after being confined to an immigration hotel for four nights - a drama that has gripped many in Australia and beyond.

Federal Circuit Court Judge Anthony Kelly reinstated Djokovic's visa, which was pulled after his arrival last week because officials said he didn't qualify for an exemption to a rule that all non-citizens be fully vaccinated. Djokovic's lawyers say that since he recently recovered from COVID-19, he didn't need to be inoculated.

The judge ruled the No. 1 player had not been given enough time to speak to his lawyers before the decision was made and ordered the government to release him from the Melbourne quarantine hotel where he was held.

But government lawyer Christopher Tran told the judge that the immigration minister "will consider whether to exercise a personal power of cancellation."

That would mean that the nine-time Australian Open winner and defending champion could again face deportation and could miss the tournament, which starts on Jan. 17. It could also bar him from the country for three years.

Late Monday night, Djokovic tweeted out a photo that showed him and his team standing on one of the main show courts of the tournament. He was already back to training, his brother told reporters in Serbia.

"I'm pleased and grateful that the Judge overturned my visa cancellation. Despite all that has happened, I want to stay and try to compete @AustralianOpen," Djokovic said in the post.

The back and forth has caused a furor in Australia, where many initially decried the news that Djokovic, who has been a vocal skeptic of vaccines, had received an exemption to strict rules to compete in Melbourne. Many felt the star, who court documents say is not inoculated, was being given special treatment since Australians who aren't vaccinated face tough travel and quarantine restrictions.

But when border police then blocked the 34-year-old on arrival, others cried foul, saying he was being scapegoated by an Australian government facing criticism for its recent handling of the pandemic.

The tennis star's brother, Djordje Djokovic, told television network Prva in Belgrade, Serbia: "This is definitely politics, all this was politics."

Spanish tennis star Rafael Nadal called the controversy "a circus" and said he supported the decision allowing his rival to play in Melbourne.

"Beyond me agreeing or not with Djokovic on certain things, there's no question that justice has spoken and has said that he has the right to take part in the Australian Open," Nadal said Monday during an interview with Spain's Onda Cero radio.

Prime Minister Scott Morrison's conservative government is seeking re-election for a fourth term in polls due by May.

While his government was widely praised for containing the nation's COVID-19 death toll at the start of the pandemic, he has recently loosened some rules, just as omicron cases have been rapidly surging. He has been criticized for that strategy as well as for shortages of rapid antigen tests and for refusing to make the tests available to all for free.

At Monday's court hearing, Djokovic's lawyers argued their client did not need proof of vaccination because he had evidence that he had been infected with the coronavirus last month.

Australian medical authorities have ruled that people who have been infected with COVID-19 within six months can receive a temporary exemption to the vaccination rule.

Judge Kelly noted that Djokovic had provided officials at Melbourne's airport with a medical exemption given him by Tennis Australia and two medical panels.

"The point I'm somewhat agitated about is what more could this man have done?" Kelly asked Djokovic's lawyer, Nick Wood.

Wood agreed that his client could not have done more, noting that transcripts of Djokovic's interview with Border Force officials and his own affidavit revealed that he repeatedly told officers he had done everything he thought was required of him.

Djokovic's lawyers described the cancellation as "seriously illogical."

But lawyers for Home Affairs Minister Andrews said in their submission that the vaccination exemption could only be granted for travelers who had recovered from a serious bout of COVID-19.

"There is no suggestion that the applicant (Djokovic) had 'acute major medical illness' in December" when he tested positive, the written submission said.

But in the end, the government lawyers conceded that the decision to proceed with interviewing Djokovic in the early hours of Thursday and cancel his visa before he could contact Tennis Australia or his lawyers was unreasonable.

Djokovic was told at 5:20 a.m. on Thursday that he had until 8:30 a.m. to respond to a notice of intention to cancel his visa. His comments were sought instead at 6:14 a.m.

The decision to cancel his visa was made just over an hour later.

Minister Andrews did not immediately responded to a request for comment. But a spokesperson for Alex Hawke, minister for immigration, citizenship, migrant services and multicultural affairs, acknowledged the court's decision, adding the minister's personal discretion remains in play.

"The minister is currently considering the matter and the process remains ongoing," the spokesman said.

Still, at a news conference in Belgrade, Serbia, Djokovic's family declared victory.

"This is his greatest victory, greater than all the Grand Slams that he has won," his mother, Dijana Djokovic, said.

The virtual hearing crashed several times because of an overwhelming number of people from around the world trying to watch the proceedings.

At one point, an expired court link was apparently hacked and broadcast pornography, The New Daily News website reported.

Djokovic has 20 Grand Slam singles titles, a men's record he shares with Roger Federer and Rafael Nadal.

From The Associated Press