ROME -- Jennifer Capriati fought the urge to be aggressive, and her patience was rewarded with a berth in the quarterfinals of the Italian Open.
The fifth-seeded Capriati beat Nadia Petrova 7-5, 6-3 Thursday to advance. She was joined in the quarterfinals by Serena Williams, Kim Clijsters and Amelie Mauresmo, who also won in straight sets in the key clay-court tuneup for the French Open.
The top-ranked Williams defeated France's Nathalie Dechy 6-3, 6-0; second-seeded Clijsters beat Cara Black of Zimbabwe 6-0, 6-3; fourth-seeded Mauresmo defeated Anna Pistolesi of 6-0, 6-3; and fifth-seeded Capriati beat Nadia Petrova 7-5, 6-3.
Capriati, who lost to Clijsters in the German Open semifinals, had a tough time against Petrova.
Petrova's powerful first serve forced Capriati to be patient in choosing when to attack. After a close first set, Capriati closed out the match with a break of serve when Petrova missed on a forehand.
"She has a lot of potential with her serve," Capriati said. "I just had to hang in there and handle the pace pretty well. It was a different type of match for me because I hadn't played that kind of tennis on clay yet.
"I feel like I'm doing everything, playing good clay-court tennis, just moving the ball around."
Williams seemed to improve as her match moved along. After taking complete control in the second set, Williams compiled a total of 32 winners, seven unforced errors and no double faults.
Clijsters dominated an opponent for the second straight match, getting past Black in 55 minutes. On Wednesday, she beat Spain's Virginia Ruano Pascual 6-1, 6-0 in 39 minutes.
Clijsters has reached the semifinals in her first seven tournaments this year. On Sunday, she squandered three match points before losing to fellow Belgian Justine Henin-Hardenne in the German Open final.
Clijsters played her 10th straight match on clay as she prepared for Roland Garros.
"I think on clay especially you need a lot of matches to really get your game up there," Clijsters said. "The balls come back a little bit more and they're not as hard."
Mauresmo beat Pistolesi for the third time in three weeks. She improved to 4-1 overall against Pistolesi, who was known as Anna Smashnova before marrying former Italian player Claudio Pistolesi in December.
In another match, four-time champion Conchita Martinez defeated seventh-seeded Daniela Hantuchova 6-3, 6-3.
Martinez won nine straight points in the second set and rallied from an 0-2 deficit to advance. She next plays Williams.
Martinez, who won four straight titles at Foro Italico between 1993 and 1996, improved her overall record in Rome to 48-7.
Also, eighth-seeded Anastasia Myskina defeated fellow Russian Svetlana Kuznetsova 6-4, 7-5; 13th-seeded Ai Sugiyama beat Patty Schnyder 6-2, 6-1; and Tina Pisnik overcame a loss in the first set to beat Emilie Loit 2-6, 6-4, 6-1.
In doubles, 46-year-old Martina Navratilova and the 17-year-old Kuznetsova defeated Janet Lee and Wynne Prakusya 7-5, 6-4.