BRISBANE, Australia (AP) — Novak Djokovic’s chance to play for a 10th Australian Open title has been thrown into limbo. 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 landed in Australia late Wednesday after receiving a medical exemption from the Victoria state government that would shield him from the strict vaccination rules in place for this year’s first major tennis tournament. But border authorities did not accept his evidence to support the exemption. The Australian Border Force issued a statement saying Djokovic failed to meet entry requirements.