Roger Federer says that world No. 1 Rafael Nadal is capable of sweeping the clay court season again. In 2010, Nadal won Monte Carlo, Rome, Madrid and Roland Garros. This year, Nadal has put Barcelona back on his schedule again.

"It's always a tough surface to try to dominate—except if you're Rafa—let's put it that way," said the third-ranked Swiss, who is on the opposite side of the Monte Carlo draw as Nadal after No. 2 Novak Djokovic pulled out. "I guess it depends a lot on Rafa, If he's able to defend everything he did last year, it's going to be tough for anybody."

Federer is 4,320 points behind Nadal in the rankings, but Nadal has to defend 7,000 points between Monte Carlo and Wimbledon, where he also won the 2010 title.

"I can take a huge step forward if I go really deep here in Monaco and also in Rome, and so forth," Federer said. "Clearly I don't have much to defend at the French and Wimbledon, I'll have some opportunities as well, especially when the Slams roll around. There's a lot to play for us in the next three, four months. Sure, I know Rafa has a lot of pressure, but I don't think that matters that much for him, especially on this surface. He's so confident, he's so good, I definitely could see him doing it again. But there's other guys that have something to say. I hope I'm one of those guys."—Matthew Cronin