### Instruction: Why is Rafael Nadal so successful on clay courts?
### Response: There are a lot of factors contributing to Rafael Nadal's success on clay. It starts with his preferred play style, heavy topspin. Heavily top spun ball bites into the surface more and jumped up higher, making it harder for the opponents to get the ball back. Next is his physical prowess -- clay courts are slow, which leads to longer points, so the players have to be in fantastic physical shape for them to keep playing at their best levels for 3-4 hours on average. Finally, Rafael Nadal's attitude and competitive spirit -- never give up, always plays with a high-intensity point in point out, and plays the sport with humility make him the ultimate champion he is on clay courts.