Fourth-seeded Russian Nadia Petrova, still seeking that elusive first WTA Tour title, cruised into the third round of the 585,000-dollar tournament here on Wednesday.
Petrova beat American wild card Jill Craybas 6-3, 6-1 on Wednesday.
Petrova, 22, has won 11 doubles titles but has yet to lift a singles crown, though she has been a runner-up in three tournaments since turning pro in September 1999.
Elena Dementieva agreed her Fed Cup teammate is the most successful current player on the WTA Tour not to win a title.
"Yes, I think she is, but it's not easy to win a title," Dementieva said. "I think that's one more step that she can do because she has a pretty solid game. She's still pretty young."
The third-seeded Dementieva joined Petrova in the third round by ousting unseeded Australian Samantha Stosur 6-4, 6-3, despite serving up eight double faults.
"I was struggling with my serve the whole match," said Dementieva, who rebounded from a second-round upset to China's rising star Peng Shuai in San Diego last week. "I was kind of nervous and couldn't do the right motion. But I didn't want to stay and play three sets, it was hot and she was in good shape. So I started go for winners."
Dementieva next will face French lefthander Marion Bartoli, who defeated China's Sun Tiantian 6-7 (4/7), 6-3, 6-1.
The night session featured second seed and reigning US Open champion Svetlana Kuznetsova of Russia against Eleni Daniilidou of Greece and fifth-seeded Belgian Kim Clijsters v Croatian Karolina Sprem.
Earlier in the day, sixth-seeded Mary Pierce of France, who lifted the crown in San Diego on Sunday, was forced to withdraw hours before her scheduled match against Tathiana Garbin of Italy after suffering a right thigh strain while practicing on Tuesday.
"I was practicing yesterday and it was at the very end when I was hitting some serves that I felt it on the serve," said Pierce, ranked 14th in the world. "I continued to finish my practice and was feeling it on every serve I was hitting."
Pierce had been enjoying a successful summer season. The two-time Grand Slam champion won her 17th career title and first US outdoor hardcourt crown Sunday.
"I'm really disappointed because I've been playing really well," said Pierce, who had won 16 of her last 18 matches, including a run to the French Open final and a quarter-final showing at Wimbledon. "I was looking forward to continuing my performance of last week into this week as well."