Top-seeded Samantha Stosur was among the winners on the opening day of play Monday at the HP Open.
Stosur cruised to a 6-4, 6-2 win over Japan's Erika Sema. It's been a somewhat tough year for the Australian, who won this title in 2009 and was also the runner-up last year, falling in the final to Marion Bartoli.
The 2011 U.S. Open champ has yet to win a tournament since her breakthrough Grand Slam title last year at Flushing Meadows. She was the runner-up in Doha back in February after a first-round flameout at the Australian Open and has yet to reach another final.
After a quarterfinal appearance at this year's U.S. Open, Stosur reached the semifinals in Tokyo to start the Asian swing before a loss in her first match last week in Beijing.
Ranked ninth in the world, Stosur is the lone member of the top 20 in this week's field.
American Christina McHale was the only other seeded player in action on Monday and the third seed was shown a quick exit by Taiwan's Kai-Chen Chang in a 6-3, 7-6 (7-5) decision.
Other winners Monday included American Jamie Hampton, Australian Casey Dellacqua, Japan native Misaki Doi, Britain's Heather Watson and Frenchwoman Pauline Parmentier.
Hampton knocked off a crowd favorite in Japan's Ayumi Morita, 6-3, 6-2, while Dellacqua bounced Japanese veteran and 2010 Osaka runner-up Kimiko Date-Krumm, 6-3, 3-6, 6-4. Doi gave the home crowd something to cheer about with a 7-5, 3-6, 6-0 triumph over American Julia Cohen, while Watson and Parmentier were both straight-set winners. Watson toppled Slovenia's Polona Hercog, 6-4, 6-4, and Parmentier dumped countrymate Mathilde Johansson, 6-2, 6-2.
First-round play will continue Tuesday with second-seeded Zheng Jie in action against Spain's Maria Jose Martinez Sanchez. Fourth-seeded Francesca Schiavone, the 2009 runner-up, will meet Russian qualifier Olga Puchkova and fifth-seeded Yaroslava Shvedova of Kazakhstan will face Thai wild card Tamarine Tanasugarn, the 2010 champ.
This year's winner will earn a first prize of $37,000.