Novak Djokovic has been denied entry to Australia and faces deportation, after his visa was cancelled amid a row over a medical exemption from COVID-19 vaccination rules.
The tennis star's hopes of defending his Australian Open title later this month now appear over.
Border officials said the world number one failed to provide appropriate evidence to meet the country's entry requirements.
The 34-year-old Serbian player had been held up for several hours at Melbourne Airport by a visa error and was ultimately refused entry.
But court documents show that his lawyers are planning to appeal against the decision.
Djokovic, who has repeatedly declined to say whether he has been jabbed against coronavirus, said on Tuesday he had received an exemption to compete in the nation's top tennis tournament.
But on landing in Melbourne late on Wednesday, the 20-time Grand Slam winner was waiting for permission to enter the country after his team had reportedly applied for a visa that does not allow for medical exemptions for being unvaccinated.
The sportsman has now been issued a letter by the Australian government saying his visa was denied and he would be deported.
He is currently believed to be quarantined at a hotel in the city.
During a news conference, Australian Prime Minister Scott Morrison told reporters: "On the issue of Mr Djokovic, rules are rules and there are no special cases.
"It's been our government's strong border policies and particularly in relation to the pandemic, that has ensured that Australia has one of lowest death rates from COVID anywhere in the world.
"We will continue to make the right decisions when it comes to securing Australian borders in relation to this pandemic."
In a statement, the Australian Border Force (ABF) says it will "continue to ensure that those who arrive at our border comply with our laws and entry requirements."
"The ABF can confirm that Mr Djokovic failed to provide appropriate evidence to meet the entry requirements to Australia, and his visa has been subsequently cancelled.
"Non-citizens who do not hold a valid visa on entry or who have had their visa cancelled will be detained and removed from Australia.
"The ABF can confirm Mr Djokovic had access to his phone", it adds.
Before the announcement, Djokovic's coach Goran Ivanisevic posted a selfie on Instagram from the airport lounge with the caption: "Not the most usual trip Down Under."
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Border officials had earlier contacted government officials in Victoria to sponsor Djokovic's visa.
But they refused to do so and he was forced to wait for hours.
He was questioned by border officials, and his father Srdjan said his son spent time alone in a room guarded by police outside.
The Serbian president, Aleksandar Vucic, criticised the "harassment" of the country's sporting star - saying he had spoken on the phone to him and offered his support.
Mr Vucic said: "I told our Novak that the whole of Serbia is with him and that our bodies are doing everything to see that the harassment of the world's best tennis player is brought to an end immediately.
"In line with all norms of international law, Serbia will fight for Novak, truth and justice. Novak is strong, as we all know."
Mr Morrison earlier said the tennis champion would be "on the next plane home" if he was unable to provide "acceptable proof" for a COVID vaccination exemption.
Rules in Victoria, where the tournament begins on January 17th, state players must be double-jabbed against COVID.
Australians had called the decision to give the top tennis star a medical exemption to enter the country "a slap in the face" after they endured months of harsh lockdowns.
Djokovic has not made public on what grounds his exemption had been granted.
But a possible explanation is that he contracted coronavirus for a second time at some point in the last six months, having previously caught it during his Adria Tour event in Belgrade in 2020.
That would negate the need for vaccination, according to rules published last year by one of two independent medical panels involved in the decision to grant him an exemption.
Only 26 people connected with the Australian Open applied for a medical exemption and just a "handful" - estimated to be around five - were granted, according to tournament boss Craig Tiley.
Reporting by: IRN