Serbia's Novak Djokovic returns the ball during a tennis doubles match with Jelena Jankovic against Serbia's Nenad Zimonjic and Olga Danilovic at charity tournament Adria Tour, in Belgrade, Serbia, Friday, June 12, 2020. Serbian tennis player Novak Djokovic set up a series of tennis tournaments in the Balkan region while the sport is suspended amid the coronavirus pandemic. (AP Photo/Darko Vojinovic)