Wozniacki needed only one hour and 20 minutes to outclass Jarmila Gajdosova from Australia 6-2, 6-3 while Zvonareva survived a worrying second set slump to beat Klara Zakopalova of Czech Republic 6-3, 4-6, 6-2.

　　The China Open, which ran in its eighth year, was hit by seed casualty again on the fourth matchday as world number seven Samantha Stosur went down to the 27th ranked Maria Kirilenko 7-5, 1-6, 7-5 after two hours' toil.

　　She joined two other reigning Grand Slam winners Li Na (French Open) and Petra Kvitova of Czech Republic (Wimbledon) in the stars' early exit, definitely reducing the box office of the elite tournament after the likes of world number one Novak Djokovic, Maria Sharapova and the Williams sisters pulled out citing injury or illness.

　　"I've only played two tournaments since winning the U.S. Open so it's not the end of the world. Obviously I wanted it to be a lot better than what it has been, but I guess it's one of those things," Stosur said.

　　With the convincing victory, Kirilenko, the 2005 China Open champion, improved her record against Stosur to 4-4.

　　Stosur just produced an impressive display from the baseline in the second set, but it was not enough for the Australian who dished up too many grave mistakes in the first and third sets.

　　"I played against her eight times in my life and now we have an even score in all matches. I know how she's playing, nothing new," Kirilenko, 24, commented on the rivalry.

　　Stosur shared the same sentiment with Kirilenko. "I don't think there's anything really bad with the tactics going out to play Maria. I think in the U.S. Open I won in three sets; last week I lost 6-4 in the third, so there is reall not a lot in it. It's just a matter of at those crucial times doing my game plan and really sticking to it when it really matters," she said.