Top seed Lindsay Davenport edged a two-and-a-half-hour see-saw marathon against Virginie Razzano 7-5 4-6 6-4 to reach the French Open fourth round.
In the last 32, she will play 14th seed Kim Clijsters, who beat 20th seed Daniela Hantuchova in straight sets.
Also through to the fourth round is fourth seed Elena Dementieva and eighth seed Patty Schnyder.
French player Mary Pierce, champion in 2000, rolled back the years to beat ninth seed Vera Zvonareva 7-6 7-5.
The 30-year-old Pierce, who earlier this week became only the 10th woman to notch up 40 singles victories at the French Open, was cheered all the way by a partisan Parisian crowd.
Russian Zvonareva served for the first set but lost her nerve, allowed Pierce to claim it on the tiebreak.
The players traded several breaks in the second set before the French 21st seed finally prevailed.
Davenport's victory was a gruelling affair with both her and Razzano reaching double figures in double faults but Davenport finally edged a see-saw battle
Davenport went 4-0 down in the first set against Razzano before fighting back to take it 7-5, only for the Frenchwoman to level in the second.
The 28-year-old world number one admitted that her play had been "erratic" during the first week in Paris.
"All my matches have gone to three sets and I struggled in all three. I'm pretty amazed I'm still here," she said.
"I'll definitely have to do things differently and play better. Maybe it will start to click."
Belgian Clijsters, twice runner-up at Roland Garros, wore down Slovakian Hantuchova 6-4 6-2 on a baking hot day in Paris.
There were five consecutive breaks of serve in the first set before 14th seed Clijsters established her authority to clinch it 6-4 after 52 minutes.
Hantuchova's resolve seemed to fizzle out after that and two breaks in the second set secured Clijsters' victory.
It was 21-year-old Clijsters' fifth win against Hantuchova in their five meetings.
She leads Davenport 9-6 in head-to-head meetings but the pair have never met on clay.
"It's not the favourite surface for either of us but I know I will have to raise my game against her," said Clijsters.
But she added: "I'm working my way into my matches, and I'm winning them. I feel like every match is getting a little bit better. I haven't lost a set yet, so I'm not complaining."
Dementieva served 19 double faults against Japan's Akiko Morigami but still came through 6-3 4-6 6-3.
She will play Russian compatriot Elena Likhovtseva next after the 16th seed beat Silvia Farina Elia 7-5 7-6.
Swiss player Schynder dropped the opening set against Flavia Pennetta of Italy but came back strongly to win 4-6 6-0 6-1.