The 24-year-old top-seed survived a roller coaster ride to move into the round of 16 for the fourth time.

    After producing an impressive display, Federer suffered a setback midway through the match but prevailed 6-1, 6-2, 6-7 (7-4),7-5 over the power-hitting Chilean in two hours and 35 minutes.

    "I'm not going to cry over it. It was a pity I couldn't close it out in two sets," said Federer.

    "At the end he was playing much better than in the beginning. He had the momentum. He wasn't missing much.

    "He's the most experienced player I've played so far here. I was surprised I dominated the two first sets so easily. I knew going in it was going to be a tough match anyway."

    Defending champion Rafael Nadal, Kim Clijsters and Martina Hingis all recorded quick-fire second round wins after their matches were postponed due to rain on Thursday.

    French top seed Amelie Mauresmo passed a tough test against world number 32 Jelena Jankovic with some assurance on center court to reach the fourth round. She won 6-3, 6-3.

    Wimbledon champion Venus Williams was too strong for Croatia's Karolina Sprem. The 2002 runner-up won 7-5, 6-3 to set up a fourth round meeting with Swiss seventh seed Patty Schnyder.

    Maria Sharapova set up an all-Russian fourth round match-up with a 6-0, 7-5 victory over Alicia Molik. The fourth seed will meet the streaking Dinara Safina in the round of 16.

    Sharapova, still dealing with a foot injury that kept her off Tour for almost two months before Roland Garros, disposed of the tall Australian in 69 minutes, most of which was the second set, when Molik found her stride and Sharapova slumped a bit.

    Nadal, who turns 20 on Saturday, crushed American Kevin Kim 6-2,6-1, 6-4 to extend his winning streak on clay to 55 matches.

    Nadal nailed 27 winners and committed an equal amount of unforced errors, while Kim only managed 20 winners and committed 40 unforced errors.

    "I began bad," Nadal said. "A little bit nervous. I was not touching the ball well. I improved in the final part of first set. In the second I improved and played better. In the third I made a break and finished. A normal match. Nothing special."

    Clijsters and Hingis, the second and 12th seeds, are potential quarter-final opponents in their quest for a maiden Roland Garros title.

    Clijsters, twice a runner-up here, beat Conchita Martinez Granados of Spain 6-0, 6-3 and Hingis, who is back at the French Open for the first time since 2001, crushed Czech Zuzana Ondraskova 6-1, 6-3.

    Argentine 10th seed Gaston Gaudio, the 2004 men's champion, won his battle with 2003 champion Juan Carlos Ferrero of Spain, winning three tight sets 7-5, 7-5, 7-6 to reach the fourth round.

    Third seeded Argentinian David Nalbandian came back from two sets down to beat Russia's Dmitry Tursunov 2-6, 5-7, 6-4, 6-2, 6-4 and now meets compatriot and qualifier Martin Vassallo Arguello for a place in the quarter-finals.

    America's James Blake, the eighth seed, recovered from a first set loss to defeat dangerous Spanish teenager Nicolas Almagro.

    Blake had dropped the opening set when play was suspended on Thursday but he thrived in the sunnier, faster conditions on Friday to record a 6-7 (5-7), 6-2, 6-4, 6-4 win.

    The American faces French 25th seed Gael Monfils for a place in the last 16.

    Croatian 12th seed Mario Ancic made the fourth round for the first time with a 6-1, 6-2, 6-4 win over Spain's Albert Montanes.

    Ancic will face Spanish seventh seed Tommy Robredo who put out the Czech Republic's Lukas Dlouhy 6-1, 6-4, 6-2.

    China's interest in the singles event ended when its top player Li Na lost 6-3, 7-6 to Russia's Svetlana Kuznetsova, who has a date against ninth seed Francesca Schiavone of Italy next.

    Earlier, Zheng Jie failed to make the third round after going down 6-4, 6-4 against Ivana Lisjak of Croatia.

    Switzerland's Patty Schnyder, the Swiss seventh seed, reached the fourth round with a 2-6, 7-5, 6-0 win over Julia Vakulenko of Ukraine.