The eight-time Grand Slam champion was broken four times in the first set, and again in the opening game of the second, before she found her rhythm and cruised through the remainder of the match.

"I've never gone down in the first round," said Williams, who won the French Open in 2002. "I can breathe now. My goal is to stay not losing in the first round of a Grand Slam."

Marat Safin was the only player to complete a match before soft, persistent rain halted play for about 5-plus hours.

The two-time Grand Slam champion beat Fernando Vicente of Spain 6-1, 6-3, 6-1 as rain started to fall at Roland Garros, suspending other matches.

No. 1 Justine Henin advanced to the second round by beating Elena Vesnina of Russia 6-4, 6-3. Her match was the only one to be completed that didn't start in the morning.

Seventeen of the 24 scheduled matches were postponed because of weather.

Tamira Paszek of Austria, who was one game away from the second round when rain halted her match, beat Aiko Nakamura of Japan 6-4, 6-0. Dinara Safina of Russia defeated Yuliana Fedak of Ukraine 7-5, 6-4.

On the men's side, Potito Starace of Italy beat Ivo Minar of the Czech Republic 4-6, 6-1, 6-4, 7-6 (5), and Janko Tipsarevic defeated Dusan Vemic 7-6 (3), 6-4, 4-6, 6-3 in an all-Serb match.

Williams was somewhat thankful for the wet conditions.

The Australian Open champion pleaded with the chair umpire to stop play while trailing 5-4 with Pironkova serving for the first set for the second time. But play continued and Williams broke to get to 5-5.

After Pironkova broke again, play was halted with the Bulgarian leading 6-5.

"In the rain ... it was really slick on the lines," Williams said. "Going back it wasn't as rainy."

Pironkova held when play resumed to win the first set, and then broke Williams in the opening game of the second. The Bulgarian won only one more game in the match.

"I pretty much should have won that (first) set," Williams said. "I'm a perfectionist, and I'm always trying to make things perfect."

Safin hit two aces in his opening service game en route to taking eight straight games, before Vicente broke in the third game of the second set.

"It's tough to play with this weather because it's raining, it's not raining, it's windy, and then it's very rough conditions because everything depends on the weather," said Safin, who has not won consecutive matches since March.

The 22nd-seeded Russian converted eight of 14 break points, and his confidence showed in the first game of the third set. He attempted a drop shot that was too short, giving Vicente an easy winner. But instead of trying to retrieve the shot, Safin turned his back and walked away — knowing he could afford to concede the point.

"I think I can manage to pass two rounds," Safin said. "Then I'll be dangerous."

Safin, who lost in the first round last year but reached the semifinals in 2002, won on Vicente's second double-fault.

Vicente, a 30-year-old veteran who has been hobbled by injuries, has lost 12 straight tour matches and had to go through qualifying to reach the men's draw.

"It was difficult for him to play at a good level in order to beat me," Safin said. "But you have to give him credit. To pass the qualies and to make sure and stick around when you are 30 years old ... it's pretty tough."

Safin will play the 80th-ranked Tipsarevic in the next round.

Last year in the quarterfinals of the Kremlin Cup, Safin was stretched to three sets before beating Tipsarevic.