French Open 2013: Victoria Azarenka into third round
Third seed Victoria Azarenka reached the French Open third round with a 6-4 6-3 victory over Germany's Annika Beck.
But 2011 champion and sixth seed Li Na lost 5-7 6-3 6-2 to American Bethanie Mattek-Sands on a day interrupted by several rain delays at Roland Garros.
Defending champion Maria Sharapova led Eugenie Bouchard of Canada 6-2 4-2 when play was suspended for a final time.
Ninth seed Sam Stosur will play 18th seed Jelena Jankovic next after both won in straight sets.
Britain's Dominic Inglot and his partner Treat Huey won through to round two of the men's doubles.
Inglot and his Filipino partner Huey beat Tobias Kamke and Florian Mayer of Germany 7-6 (7-5) 6-4.
British pair Colin Fleming and Jonathan Marray were beaten 7-6 (7-4) 6-7 (3-7) 7-5 by Feliciano Lopez and Andre Sa.
Heather Watson and her Ukrainian partner Irina Buryachok went out of the women's doubles 3-6 6-4 7-5 to Oksana Kalashnikova and Alicja Rosolska.
Belarus's Azarenka, 23, faces Alize Cornet next after the French 31st seed beat Spain's Silvia Soler-Espinosa 6-1 6-3.
Mattek-Sands's best Grand Slam showing came at Wimbledon in 2008, when she reached the fourth round.
She appeared on the verge of defeat in the second set when rain prompted a 90-minute delay but was a different player on her return.
"I wanted to play aggressive, and that's what I did," said Mattek-Sands, the world number 67. "That's one of the best wins of my career."
"I was a little bit surprised today the way she's hitting," said Li. "Well done for her. The weather didn't change anything - for both of us it was the same."
Australia's Stosur beat Kristina Mladenovic 6-4 6-3 and Serbia's Jankovic beat Garbine Muguruza 6-3 6-0.
Other women who managed to defy the rain and win a place in the third round were former Wimbledon champion Petra Kvitova, the seventh seed, and American 17th seed Sloane Stephens.