Serena Williams thinks the most impressive thing about Roger Federer is that he is holding 20 Grand Slam titles.
“I think it's impossible to say which one is greater,” said Serena.
“I mean, I think Roger is a great player. He's done so much for the game and the sport. He's just an unbelievable athlete and unbelievable player. He's been playing for a long time in his career. Obviously, it was longer. Rafael, on the other hand, started younger, starting winning Grand Slams really young, and he's a great, great player as well. If you're going by numbers, Roger still has more Grand Slams than Rafa, so you have to go with that.”