(CNN) -- Defending women's champion Svetlana Kuznetsova survived four match points before scraping into the third round of the French Open on a rain-interrupted fourth day at Roland Garros.
The sixth seeded Russian was on the brink of losing to 41st-ranked German Andrea Petkovic but rallied to prevail 4-6 7-5 6-4.
Petkovic served for the match at 5-4 in the second set but produced unforced errors on all four of her match points.
Kuznetsova raced into a 5-2 lead in the decider and eventually clinched her fourth match point to prevail.
Venus Williams had a more straightforward path to round three with a 6-2 6-4 victory over Spain's Arantxa Parra Santonja.
The American will next play Dominika Cibulkova, who came from a set down to beat Varvara Lepchenko.
"She definitely kept me on my toes," Williams told reporters in Paris. "Overall today I just thought I played you the bigger points really well, and I think that was key."
Elsewhere, there were wins for Caroline Wozniacki, Nadia Petrova and 15th seed Aravane Rezai, who beat Williams at the Madrid Open final earlier this month.
In the men's competition, defending champion Roger Federer endured two weather delays before overcoming Alejandro Falla 7-6 (7/4), 6-2, 6-4.
Federer was given a tough time by the talented Colombian, who looked on course to take the first set after breaking his opponent at five-all.
But Federer showed why he is world number one by breaking straight back and firing four winners to take the tie-break.
"I think he really pushed me to come up with something special," said Federer. "I think it was special what he was able to do today."
The second and third sets were more straightforward for Federer will play Julian Reister of Germany in the next round.
Last year's runner-up Robin Soderling hammered Taylor Dent of the U.S. 6-0 6-1 6-1 and Jo-Wilfried Tsonga thrashed fellow Frenchman Josselin Ouanna 6-0 6-1 6-4.
Fourth seed Andy Murray's contest with Juan Ignacio Chela will resume on Thursday after being abandoned due to bad light with the Briton leading the Argentine 6-2 3-3.
Meanwhile, Fabio Fognini and Gael Monfils played on in near darkness on the Phillipe Chartrier court before finally calling it a day at 5-5 in the fifth set at 9.56pm local time after the Frenchman had saved three match points.