Novak Djokovic has won an appeal to stay in Australia, with a judge freeing him from hotel detention, but the government may still choose to deport him.

The tennis star had been forced to stay in the Melbourne hotel after being blocked by border officials last week ahead of the Australian Open.

Djokovic believes his COVID infection last month means he is exempt from a rule that non-Australians must be vaccinated.

However, Djokovic's father told Sky News this morning that his son had been "arrested" by the Australian government - a claim that has not yet been verified.

Judge Anthony Kelly said Djokovic had provided border officials with a medical exemption given to him by Tennis Australia and two medical panels.

"The point I'm somewhat agitated about is what more could this man have done?" Mr Kelly said.

The judge quashed the decision to revoke the visa, saying it was "unreasonable" - and that the player hadn't been given enough time to respond after being notified of the cancellation.

What tennis star told border officials

Djokovic had told border officials he was unvaccinated and had been infected with COVID twice, according to a transcript of an interview revealed in court.

The player has never publicly revealed his vaccination status.

Airport officials also made him switch off his phone from midnight to around 7:42 am, when the decision to cancel his visa was made, the judge added.

A group of around 50 supporters, many draped in the Serbian flag, celebrated outside the Melbourne court following the judge's decision.

However, it may not be the end of the row.

Government could still deport Djokovic

Lawyers for immigration minister Alex Hawke said he was reserving the right to exercise his power to again revoke the visa.

"The minister is currently considering the matter and the process remains ongoing," a spokesperson added.

Sky reporter Nicole Johnston, outside the detention hotel, said: "Essentially the court found there was a failure in due process - that it wasn't fair - so for now we wait to hear from the federal government."

Djokovic gave evidence of COVID infection

The Australian Open begins on 17 January, with the Serbian star bidding to become the most successful men's player ever.

Djokovic's lawyers said the player should have been allowed entry because he had recently had COVID and "was entitled to a medical exemption in accordance with Australian government rules".

They filed papers that showed he tested positive last month and recovered.

Djokovic provided evidence before he travelled to Australia and when he landed on Wednesday, the court heard.

Lawyers also showed that the 34-year-old had received a letter from Tennis Australia's chief medical officer on 30 December stating that he had been exempted on these grounds.

It said Djokovic's positive COVID test was on 16 December and, on the date of issue, he "had not had a fever or respiratory symptoms in the past 72 hours".

However, government lawyers told the court that travellers could only be exempt from vaccination if they had been seriously sick with COVID.

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

Unmasked photos

Photos have emerged in the last few days of the world number one - without a mask - with young players the day after he's said to have tested positive.

It is not clear if Djokovic knew the results of his test at the time.

On the day he tested positive he was also presented with a stamp by the Serbian postal service in Belgrade, an event he tweeted about the next day.

In the next tweet, on 4 January, he said he was on his way "Down Under with an exemption permission".

Djokovic has not disclosed his vaccination status, but has previously said he wouldn't want to be compelled to get a jab to travel or play in competitions.

His case has polarised opinions, especially in Australia, which has endured some of the toughest and longest COVID lockdowns in the world.

It has also caused a political row after Prime Minister Scott Morrison said "rules are rules" and that no one would get special treatment.

He was accused of taking advantage of the case to improve his popularity ahead of elections.

After narrowly missing out on a calendar grand slam in 2021, Djokovic will be keen to try to go one ahead of Rafael Nadal and Roger Federer as the winner of the most majors.