Novak Djokovic may not defend his Australian Open title.The world's top-ranked tennis player will likely need to be fully vaccinated to get a visa into the country, which will reopen its borders in November. "You'll need to be double vaccinated to visit Australia. That's a universal application, not just to tennis players. I mean that every visitor to Australia will need to be double vaccinated," Australia's Minister for Immigration said, according to CNN. In an interview with a Serbian media outlet, Djokovic said he has no plans to reveal his vaccination status."Too many people allow themselves the freedom to ask and then to judge," Djokovic said, according to Serbian journalist Saša Ozmo."Whatever you say—I have, I have not, maybe, I do not know or I am thinking about it—they will use it against you. There is excessive speculation, from the media as well, which bothers me a lot.Tennis Australia, which oversees the first grand slam of the year, has not issued the final guidance for players. Djokovic is aiming for his 21st grand slam title, which would break the tie between him, Roger Federer and Rafael Nadal. The Australian Open is Djokovic's most successful grand slam. He has won it a record nine times.