Salary/Winnings: $17.2m Endorsements: $31m In recent years, thanks in part to the gradual decline of Roger Federer and Rafael Nadal, Novak Djokovic has ascended to his current status as the undisputed king of tennis. He recently completed an unbelievable 2015, in which he won three majors, six masters, and scooped $17.2m in winnings. Despite his unbelievable on-court performances, Djokovic's endorsement deals made up the bulk of his 2015 earnings. He currently has deals with Peugeot, Seiko, Jacob's Creek, and ANZ. However, despite being the most successful tennis star last year, he's been overshadowed by one other racket-master on this list...