Novak Djokovic, the third-ranked tennis player in the world, acknowledged on Saturday that he might not be able to compete in the U.S. Open tournament later this summer because he isn’t vaccinated. “You’re right, as of today I’m not allowed to enter the States under these circumstances,” he said in a press conference before competing at Wimbledon. “I’ll just have to wait and see... There is not much I can do anymore. I mean, it’s really up to the U.S. government to make a decision.” Current Centers for Disease Control guidelines require non-citizens to be fully vaccinated against COVID-19, with “limited exceptions.” Last winter, Djokovic became mired in a legal kerfuffle after he received a medical exemption to compete in the Australian Open, only to have authorities revoke his visa.