Australia and Serbia are at odds following the former's decision not to allow Novak Djokovic entry into the continent.

According to reports, the tennis superstar from Serbia has always been vocal about his refusal to get vaccinated. In 2020, he told reporters that he has no plans to get inoculated, especially if it becomes a requirement to travel overseas.

On Wednesday, Djokovic arrived in Australia ahead of the Australian Open. But after arriving in Melbourne, he was interviewed by airport authorities before his visa was canceled hours later.

Prior to his trip, Djokovic thought that his team managed to secure a visa that permits medical exemptions for unvaccinated athletes. But apparently, they were unable to do so.

All athletes, staff, and attendees must show proof of vaccination to attend the Australian Open on Jan. 17. A medical exemption is also given to athletes that cannot get vaccinated due to other health issues.

Australian authorities defend decision to ban Novak Djokovic

Victoria's Deputy Premier James Merlino released a statement saying that medical exemptions are not supposed to be used as loopholes for privileged tennis players. Instead, they are intended for athletes that have acute medical conditions.

Karen Andrews, Australia's home affairs minister, also said that the government has the right to refuse athletes that do not adhere to their rules.

"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," Andrews said via the Huffington Post.

Read Also: No Special Treatment: Unvaccinated Athletes Banned To Compete at the Australian Open 

Serbian president stands by Novak Djokovic

However, Serbian President Aleksandar Vucic accused Australian authorities of harassing the best tennis player in the world. He also stressed that Serbia supports Djokovic.

Djokovic is a nine-time Australian Open winner. And his inability to enter Australia could also mean that he won't be able to compete in the games.

Rafael Nadal weighs in on Novak Djokovic vaccination controversy

Fellow tennis superstar Rafael Nadal also weighed in on Australia's decision not to allow Djokovic to enter the country.

He said that he feels sorry for the tennis superstar, but he also understands that vaccination is necessary to be able to compete at the Australian Open.

Nadal went on to say that Djokovic must have known beforehand that he would face some problems due to his decision to remain unvaccinated.

He also said that he understands that everyone has the right to make their own choices, but there are also rules to follow, especially for athletes.

Previous reports claimed unvaccinated athletes need to quarantine

In October, reports claimed that unvaccinated athletes can still participate in the Australian Open as long as they quarantined for 14 days.

The reports also claimed that the unvaccinated athletes must present a negative COVID-19 test 72 hours before leaving their home country.

However, Victoria state sports minister Martin Pakula clarified that nothing had been finalized yet because authorities are still deciding on what they would do to unvaccinated athletes, according to CNN.

Related Article: Australian Open May Allow Unvaccinated Athletes To Compete After Undergoing a 14-Day Quarantine