World-renowned tennis player Novak Djokovic now finds himself at the center of a diplomatic firestorm as the Australian government keeps him detained at the Melbourne airport due to his vaccination status.

On Wednesday, Djokovic arrived at Melbourne’s Tullamarine airport after being granted a medical exemption to compete in the Australian Open, where he had hoped to earn a “record-breaking 21st Grand Slam,” according to Reuters.

The champion was subsequently denied entry into the country when the state of Victoria, where the city of Melbourne is located, said the visa he applied for did not allow for a medical exemption. As of Thursday morning, Djokovic remains stranded at the airport, reportedly alone in a room under armed guard, according to his father, Srdjan.

“I have no clue what’s going on. They’ve kept my son in captivity for five hours now,” Srdjan told the Serbian online version of Sputnik. “If they don’t let him go in half an hour, we’ll gather in the streets, this is a battle for everyone.”

TURIN, ITALY – NOVEMBER 17: Novak Djokovic of Serbia walks out prior to his singles against Andrey Rublev of Russia on Day Four of the Nitto ATP World Tour Finals at Pala Alpitour on November 17, 2021 in Turin, Italy. (Photo by Julian Finney/Getty Images)

Tensions between the tennis star’s home country of Serbia and the government down under have since escalated. In an Instagram post, Serbian president Aleksandar Vucic said that all of Serbia stands with its star citizen and will not tolerate Australia’s treatment of him.

“I’ve just finished my telephone conversation with Novak Djokovic,” 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,” he added.

BELGRADE, SERBIA – OCTOBER 07: Serbian President Aleksandar Vucic speaks during the press conference with Prince Albert II of Monaco (unseen) after their meeting at the Serbia Palace on October 7, 2020 in Belgrade, Serbia. (Photo by Srdjan Stevanovic/Getty Images)

Controversy over Djokavic’s visit to Australia has been brewing since Prime Minister Scott Morrison’s government granted him a medical exemption from the country’s vaccine mandate.

“I think it would be good for the player himself to give some explanation,” said Toni Nadal, uncle and former longtime coach to Djokovic rival Rafael Nadal, said. “He has no obligation to disclose data that belong to his privacy, but he should be aware that he is an international reference at a time of very serious world health crisis and of great sensitivity due to the enormous pain that COVID-19 is causing.”

“I would like to think that Novak is not oblivious to all this and that he will clear up any doubts as a sign of human sensitivity and understanding,” Nadal added.

Prime Minister Scott Morrison said in response to the controversy:  “We await his presentation and what evidence he provides us to support that (exemption). If that evidence is insufficient, then he won’t be treated any different to anyone else, and he’ll be on the next plane home. There should be no special rules for Novak Djokovic at all.”