Tennis world number one Novak Djokovic's lawyers have launched a Federal Circuit Court challenge to the Australian federal government's decision to deport him.
The 34-year-old landed at Melbourne's Tullamarine airport late last night and was detained by Australian Border Force (ABF) officials.
In a statement, the ABF confirmed Djokovic did not meet the entry requirements and his visa was 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 statement said.
Border Force officials are also investigating another player and an official who were granted medical exemptions by Tennis Australia.
Djokovic was taken to a hotel controlled by immigration officials about 10am (Melbourne time).
He will remain in immigration detention tonight after a court appeal against the cancellation of his visa was adjourned until 10am (Melbourne time) Monday.
Lawyers for the federal Minister for Immigration said they would not oppose an interim injunction restraining the federal government from deporting Djokovic today.
Judge Anthony Kelly asked both parties to give him their submissions over the weekend.
It is expected hearings will revolve around when, or if, Djokovic will be removed from Australia.
Lawyers for Djokovic said they had been advised Tennis Australia would need a definitive answer by Tuesday for scheduling purposes.
But Judge Kelly said "the tail won't be wagging the dog here".
During the earlier hearing, Judge Kelly asked if Djokovic had "tennis practising facilities" in the hotel he was detained in and if not whether he could moved to one that did.
Other considerations discussed were whether the matter of his detention and visa would be decided before the Australian Open starts on 17 January, and what dates he is scheduled to play.
Tennis Australia and the Victorian government had earlier issued Djokovic with a medical exemption from being vaccinated against Covid-19, clearing him to travel to Australia to defend his Australian Open title.
Prime Minister Scott Morrison said Djokovic would be deported.
He said it was the player's responsibility to make sure he had the correct paperwork before arriving in Australia.
"It is for the traveller to be able to assert and back up their ability to come into the country, consistent with our laws," he said.
"They can take advice, but it is up to them at the end of the day, and if they do not comply with the rules, then the Australian Border Force will do their job and they have done their job."
The prime minister rejected claims by the Victorian government that the state had been asked by Border Force to sponsor a visa for Djokovic.
"There was inquiries being made about whether quarantining was going to be waived and to my knowledge I still don't know whether the Victorian government were proposing to waive quarantining."
-ABC