Belgium's former world number one Kim Clijsters beat Japan's Shinobu Asagoe 6-3 6-3 to reach the third round of the Pacific Life Open in Indian Wells.
The unseeded Clijsters is playing in her second tournament this season after four months out with a wrist injury.
Top seed Lindsay Davenport overcame Bulgarian Sesil Karatancheva 6-3 6-2.
Second seed Amelie Mauresmo of France beat Tathiana Garbin 6-2 6-1 and US Open champion Svetlana Kuznetsova defeated Czech Eva Birnerova 6-3 6-2.
Clijsters, who slumped to number 133 in the world rankings because of her injury problems, overcame five double faults before trumping Asagoe with a host of forehand winners.
The 2003 Pacific Open champion said: "This is my first tournament overseas in almost a year, so I was really looking forward to it.
"The main thing is that my wrist stays well and that I keep doing everything right, cool it down after matches and everything."
Reigning Wimbledon champion Maria Sharapova hit two aces and 15 winners to beat Angela Haynes 6-1 6-2 and reach the third round.
The turning point came when Sharapova broke Haynes in the sixth game of the second set to go up 4-2.
"The first match is never easy. You don't know what to expect," Sharapova said.
"I got a bit of a groove going and then I broke her three times in the first set. I took a chance and went for it on her third serving game in the second set and it paid off."
In other matches, France's Nathalie Dechy weathered a second set stumble to beat countrywoman Emilie Loit 6-4 4-6 6-3.
Sixth seed Nadia Petrova, of Russia, routed Italian Antonella Serra Zanetti 6-0 6-1.
Thirteenth seed Daniela Hantuchova went through after three tough sets against Luxembourg's Anne Kremer.
Russia's Maria Kirilenko beat eighth-seeded compatriot Elena Bovina 6-3 6-1.
Meghann Shaughnessy advanced by beating fellow American Shikha Uberoi 7-5 6-1.