Hundreds of Novak Djokovic’s supporters gathered at a rally in downtown Belgrade on Friday to protest his confinement in Australia after his entry was denied by border authorities because of COVID-19 vaccination regulations.

The top-ranked Serb, who hopes to defend his title at the Australian Open and win a men’s record 21st Grand Slam singles title, was denied entry when he arrived at Melbourne’s airport on Wednesday and was still in an immigration detention hotel awaiting a court hearing scheduled for Monday to challenge his deportation.

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The detention has triggered anger among Djokovic’s fans in his native Serbia, with his family calling for protests until he is released.

Speaking at the rally, Srdjan Djokovic described his son’s struggle to play at the Australian Open as a fight against “globalists who want to ruin everything.”

“He is fighting for himself, his people and all freedom-loving nations in the world,” said Srdjan Djokovic, an outspoken critic of the West and supporter of Serbia’s traditional Slavic ally Russia. “They hate him because Australian politicians have put pressure on people to hate him because he thinks with his own brain.”

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Djokovic’s father also said Australians “have been in captivity for two years” in reference to the strict lockdown coronavirus measures that have been in place in Melbourne.

“He (Djokovic) is in prison, not in custody, not in a hotel. They took away all his things, took away his wallet, and returned it to him after a few hours,” Srdjan Djokovic said as the crowd chanted “Monsters, Monsters.”

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He said the Australian authorities “wanted to humiliate and throw him to his knees.”

Australian officials initially said Djokovic, a vocal skeptic of vaccines who has refused to say if he has gotten the COVID-19 shot, would be given an exemption to stringent vaccine rules by state authorities and be able to participate in the Australian Open. But when he landed, his visa was canceled by federal border officials and he is now in an immigration detention hotel while he fights the decision.