Justine Henin-Hardenne and Maria Sharapova both reached the third round of the French Open in straight sets.
Tenth seed Henin-Hardenne beat Virginia Ruano Pascual 6-1 6-4 despite her serve being hampered by a back injury.
Sharapova, who could top the world rankings after this tournament, saw off French wildcard Aravane Rezai 6-3 6-2.
Also into the third round are third seed Amelie Mauresmo, sixth seed Svetlana Kuznetsova and seventh seed Nadia Petrova.
But 24th seed Magdalena Maleeva was upset 6-3 6-4 by Anabel Medina Garrigues, who won the Strasbourg International event last weekend.
Spaniard Medina Garrigues will now play Henin-Hardenne in the third round.
The Belgian is the favourite for the women's title at Roland Garros and she raced to a 5-0 lead in the first set before calling the trainer on to treat her back.
From then on, she struggled with her serve but luckily for her, Ruano Pascual produced an error-strewn performance and was unable to capitalise on her opponent's discomfort.
The Spaniard broke three times in the second set but didn't hold her own once and Henin-Hardenne squeaked through in an hour and 21 minutes.
The Belgian played down fears that the back injury could prematurely end her stay at Roland Garros.
"I have had a back problem for about two months now and it's something I have to deal with," she said.
"On clay courts, you have to be at your best level but I think I will be fine over the rest of the tournament. I called for the trainer because I wanted to make sure everything was alright.
Mauresmo dropped just two games in her second-round match
"It was hurting me when I served but it's not something I am afraid of."
Rezai briefly threatened a shock against second seed Sharapova when she broke early in the first set and led 3-1.
But Wimbledon champion Sharapova then rattled off six straight games to regain control.
Both players struggled to hold serve in the second set before Sharapova stepped up a gear to finish off the match.
Mauresmo dropped just two games against her fellow Frenchwoman, Alize Cornet.
The third seed raced to a 6-0 5-1 lead but was then broken by the 15-year-old when serving for the match.
However she immediately broke again to win 6-0 6-2 and book a third-round meeting with 29th seed Ana Ivanovic.
US Open champion Kuznetsova beat Swedish qualifier Sofia Arvidsson 6-3 6-4 while her fellow Russian Petrova beat Severine Beltrame of France 6-1 6-3.
Italian Francesca Schiavone, who is the 22nd seed, beat up-and-coming Czech teenager Nicole Vaidisova in straight sets.
Other to progress included 12th seed Russian Elena Bovina and French pair Nathalie Dechy, who is seeded 13, and Tatiana Golovin, who is seeded 17.
But 30th seed Gisela Dulko of Argentina fell in straight sets to Marissa Irvin of the United States.