FILE - Feb. 21, 2021, file photo Serbia's Novak Djokovic holds the Norman Brookes Challenge Cup after defeating Russia's Daniil Medvedev in the men's singles final at the Australian Open tennis championship in Melbourne, Australia. Players who haven't received a COVID-19 vaccination are unlikely to get a visa to enter the country for the Australian Open next January, according to the political leader of the state which hosts the season-opening major. (AP Photo/Hamish Blair, File)