"No one is unbeatable, but I'd like to see Serena play in men's tournaments: she'd win a $10,000 tournament. She has an intensity and ability to play on the court that even men don't have. I've heard a lot of talk about the difference between men and women, but Serena's strength has to be proven on the court. I train with guys who are ranked 400-500 in the world, and I can assure you that she hits much harder."