The world's best tennis players have amassed a fortune in the 2018 season. Roger Federer, Novak Djokovic, and Serena Williams have all banked millions. But who comes out on top? Tennis is one of the best-paid sports for men and women to compete in. Stars like Novak Djokovic and Roger Federer have banked well over $100 million in career earnings, while Serena Williams is not too far behind at $88 million. But how have the world's best tennis players fared in the 2018 season?