Novak Djokovic has been detained in Australia ahead of a court hearing that will determine whether the unvaccinated tennis star can stay in the country.
The Serbian faces deportation after his visa was cancelled for a second time, with the government labelling the 34-year-old a threat to public health.
His lawyers are appealing against what they called an "irrational" judgement, with the hearing set for Sunday.
Djokovic is still scheduled to play the Australian Open on Monday in Melbourne.
If he were to win the tournament, he would become the most successful men's tennis player in the history of the sport with 21 major titles.
But Sunday's hearing, which has been scheduled for 09:30 local time (22:30 GMT on Saturday), is crucial if Djokovic is to be able to compete just hours later.
If he loses the appeal, the world's top-ranked men's tennis player faces deportation and a three-year visa ban.
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On Saturday, shortly after an online pre-trial hearing, Djokovic returned to the immigration detention hotel where he was held earlier this week, He will remain there until his final appeal on Sunday.
At the procedural hearing, Justice David O'Callaghan set the time for Sunday's proceedings but said it was yet to be decided whether it would be heard by a single judge or a full court.
Djokovic's visa was first revoked shortly after his arrival in Melbourne on 6 January, after Australian Border Force officials said he had "failed to provide appropriate evidence" to receive a vaccine exemption.
The tennis star was detained for days at an immigration hotel, before his visa was reinstated by a judge, who ordered his release, ruling that border officials ignored correct procedure when he arrived.
But on Friday evening, Mr Hawke once again cancelled Djokovic's visa under separate powers in Australia's Migration Act.
The act allows him to deport anyone he deems a potential risk to "the health, safety or good order of the Australian community".
Prime Minister Scott Morrison said the decision followed "careful consideration".
Alluding to the heavy criticism his government has faced for allowing the unvaccinated player into Australia, Mr Morrison said: "Australians have made many sacrifices during this pandemic, and they rightly expect the result of those sacrifices to be protected."
BDST: 1310 HRS, JAN 11, 2022