June 26 (UPI) -- Novak Djokovic : The Wolf in Winter , a new documentary about Serbian tennis pro Novak Djokovic, will premiere on Prime Video in August. The streaming service announced an Aug. 20 release date for the feature-length documentary film in a press release Friday. The Wolf in Winter explores the life of Djokovic, 39, who "began playing on the hardscrabble courts of Serbia and rose to become the most accomplished champion in the history of men's tennis," according to an official