Updated: May 14, 2010, 1:30 PM ET

Nadal 13-0 on clay this season

Associated Press

MADRID -- Rafael Nadal cruised past Gael Monfils 6-1, 6-3 Friday to advance to the semifinals of the Madrid Masters and improve his clay-court record this season to 13-0.

Venus Williams also reached the semifinals, defeating Samantha Stosur 6-3, 6-3. Williams will play Shahar Peer, who beat Li Na 6-4, 3-6, 6-4.

Monfils was playing his first clay tournament of the season and was outclassed by a dominant Nadal, who has not lost a service game in his three matches in Madrid.

The third-ranked Spaniard pressured Monfils' serve from the start, and broke to go up 3-1 in the first set after the 12th-seeded Frenchman double-faulted. Another unforced error by Monfils gave Nadal a second break before he served out the set. 

"In the first set, I played at a very high level," Nadal said. "This is the toughest tournament for me, the conditions are the most difficult of the year for me on clay, but I'm fine."

Monfils got his two break points of the match when leading 2-1 in the second, but Nadal won the next four points and cruised through the rest of the set.

Nadal, who has won clay-court titles in Monte Carlo and Rome, is looking for a record 18th Masters title. Nadal and Andre Agassi each has won 17.

Nadal will play Spaniard Nicolas Almagro, who beat Jurgen Melzer 6-3, 6-1 in the only quarterfinal not to feature a seeded player.

Almagro broke Melzer twice to close out the first set before taking a 3-0 lead in the second with solid serving.

Williams broke the eighth-seeded Stosur's serve four times. Williams, who will improve to No. 2 behind sister Serena next week, has won all four of her meetings with the Australian.

"Her game plan seemed to be to just attack everything," Williams said. "She played well. But there were some key points, and at the end, from 4-3, I felt like I went on autopilot, so it felt good."

Despite the defeat, Stosur's recent performances are projected to send her to No. 7 in next week's rankings, the highest held by an Australian since Wendy Turnbull in 1985.

Earlier, Lucie Safarova advanced to the semifinals with a 6-1, 1-6, 6-4 victory over 16th-seeded Nadia Petrova.

Safarova has had an impressive clay-court season, reaching the quarterfinals in Stuttgart and Rome. She will face either Jelena Jankovic or Aravane Rezai.