ovak Djokovic’s chance to play for a 10th Australian Open title was thrown into limbo Thursday when the country denied him entry and canceled his visa because he failed to meet the requirements for an exemption to COVID-19 vaccination rules.

The top-ranked Djokovic announced on social media Tuesday that he had “exemption permission” and landed in Australia late Wednesday after receiving a medical exemption from the Victoria state government that was expected to shield him from the strict vaccination regulations in place for this year’s first major tennis tournament.

But border authorities did not accept the exemption. The Australian Border Force issued a statement saying Djokovic failed to meet entry requirements.

“The rule is very clear,” Prime Minister Scott Morrison told a news conference Thursday. “You need to have a medical exemption. He didn’t have a valid medical exemption. We make the call at the border, and that’s where it’s enforced.”

Health Minister Greg Hunt said the visa cancellation followed a review of Djokovic’s medical exemption by border officials who looked “at the integrity and the evidence behind it.”

He said Djokovic was free to appeal the decision, “but if a visa is canceled, somebody will have to leave the country.”

The president of Djokovic’s native Serbia blasted the “harassment” of the star, who was detained overnight at Melbourne Tullamarine Airport. The 20-time major winner had to wait more than eight hours at the airport to find out if he would be allowed into the country. He was later moved to a hotel, pending arrangements for a flight out of Australia or legal action.

Morrison confirmed the cancellation in a Twitter post: “No one is above these rules. Our strong border policies have been critical to Australia having one of the lowest death rates in the world from COVID, we are continuing to be vigilant.”

Concerns about Djokovic’s visa status started building Wednesday.

Morrison initially said the medical exemption decision was a matter for the government of Victoria, where Melbourne is the state capital.

But Home Affairs Minister Karen Andrews then clarified the border process.

“While the Victorian government and Tennis Australia may permit a non-vaccinated player to compete in the Australian Open, it is the Commonwealth government that will enforce our requirements at the Australian border,” Andrews said. “If an arriving individual is not vaccinated, they must provide acceptable proof that they cannot be vaccinated for medical reasons to be able to access the same travel arrangement as fully vaccinated travelers.”

When asked again about Djokovic’s case later Wednesday, Morrison added: “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.”