Former world No. 4 beat Federer, Nadal and Djokovic, but had to quit at 26 after serious illness

He defeated the Big 3, Roger Federer, Rafael Nadal and Novak Djokovic in unforgettable moments, but at the peak of his career, his health played a cruel trick on him.

• Former world No. 1 who crushed Djokovic, overlooked Nadal and retired at 29 admits: 'I never liked playing tennis'
• A Top 10 WTA player has more money than Federer, Djokovic, and Nadal combined at just 23 years old