The unusual sight of the sun at this year's French Open brought out the ruthless streak in Rafael Nadal [Images] and Roger Federer [Images] on Friday.

French top seed Amelie Mauresmo and rivals Kim Clijsters [Images], Maria Sharapova [Images], Martina Hingis [Images] and Venus Williams [Images] also revelled in improved conditions following the rain-soaked start to the claycourt grand slam.

A merciless Nadal left Kevin Kim gasping after a 6-2, 6-1, 6-4 second round victory over the American lucky loser.

- Images from the French Open - Day 6

"It feels like you're in the Sahara and you just see the hills, and there's no ending," said Kim after the Spanish defending champion extended his record claycourt winning streak to 55 on Court Suzanne Lenglen.

Federer, who is seeking to complete a non-calendar year grand slam, was even more impressive in the first two sets of his 6-1, 6-2, 6-7, 7-5 third round win over Chilean clay specialist Nicolas Massu.

The Swiss world number one, however, was seriously tested by Massu in the remaining two sets but the Chilean finally cracked serving at 5-6 in a tight fourth.

Also read: Bhupathi-Malisse in third round

"The first two sets were a surprise to me because I dominated it so much and that gives me extra confidence now," said the top seed. Federer will next face gifted Czech Tomas Berdych, who beat him at the Athens Olympics [Images] two years ago. Berdych's opponent Nicolas Kiefer withdrew due to a wrist injury after losing the first set 6-1.

Men's third seed David Nalbandian, survived a big fright against Russian Dmitry Tursunov [Images] and needed all his resolve to secure a 2-6, 5-7, 6-4, 6-2, 6-4 victory on his fifth match point.

Like Nadal, Clijsters and Hingis recorded quick-fire second round wins after their matches were postponed due to rain on Thursday.

Mauresmo reached the fourth round with an assured 6-3, 6-3 win over Serbian world number 32 Jelena Jankovic on centre court.

The Australian Open champion is seeking a first French Open title and so far has shown no sign of cracking under the strain of being the home favourite.

"I need to get stronger round after round and that's what I'm doing," said Mauresmo who will play 17-year-old Nicole Vaidisova, the Czech who won the Strasbourg event last week, in the last 16.

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.

Fourth seed Maria Sharapova beat Australia's Alicia Molik [Images] 6-0, 7-5. The Russian, who will play compatriot Dinara Safina in the last 16, celebrated by signing a hat held out to her from the stands by tennis-loving former Russian President Boris Yeltsin.

RAZOR-SHARP

Spaniard Nadal had not played since Monday but looked razor-sharp on Friday. He is unlikely to be daunted on Saturday, his 20th birthday, by third round opponent Paul-Henri Mathieu of France [Images]. Nadal has won all four of their previous meetings.

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 in bright sunshine.

Hingis was especially impressive in the first set. "I almost felt sorry (for her)," said the former world number one who is back playing on tour after a three-year hiatus.

"I played really well, served well, moved well. It's all coming together again."

U.S. Open champion Clijsters won her first set even more easily but was a break down at 3-2 in the second before rallying.

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

BLAKE TARGET

Gaudio will next play 2005 semi-finalist Nikolay Davydenko. The sixth-seeded Russian celebrated his 25th birthday by downing 1998 champion Carlos Moya [Images] of Spain 6-1, 7-5, 6-3.  

Eighth seed James Blake kept the American flag flying when he beat highly-rated Spaniard Nicolas Almagro 6-7, 6-2, 6-4, 6-4 to reach the third round at Roland Garros for the first time.

Blake had lost the first set on Thursday before bad light stopped play.

"I have to prove (the American coach) Brad Gilbert right," Blake said. "He said there's going to be an American in the second week. I got to make sure he's not wrong for the first time ever."

• Complete tennis coverage
• All you want to know about Sania Mirza