Guangzhou - Four of the top five seeds including number one pick Samantha Stosur crashed out of the $500 000 WTA Guangzhou Open in the first round Tuesday, as the former US Open champion's poor run of form continued.
Australian Stosur lost to home wildcard entry Wang Yafan 2-6, 6-2, 6-2, making seven double faults in a two-hour, three minute match.
On a day of shocks fourth seed Bojana Jovanovski of Serbia lost to Romanian Monica Niculescu 6-2, 6-2, while Zarina Diyas of Kazakhstan, seeded five, crashed out to Hong Kong's Zhang Ling 6-4, 6-1.
Third seed Sloane Stephens of the US lost 6-3, 4-6, 6-4 to Spain's Silvia Soler-Espinosa in the day's last match.
Stosur won the US Open in 2011, a season which saw her climb to number four in the rankings.
But she is now at 20 after failing to get past the semi-finals of any of the 18 tournament she has competed in so far this year.
Results from the Guangzhou Open WTA tennis tournament in Guangzhou on Tuesday (x denotes seedings):
Zhang Ling (HKG) bt Zarina Diyas (KAZ x5) 6-4, 6-1
Xu Yifan (CHN) bt Patricia Mayr-Achleitner (AUT) 6-2, 6-3
Hsieh Su-Wei (TPE) bt Alison Van Uytvanck (BEL) 7-6 (7/2), 2-6, 6-4
Petra Martic (CRO) bt Sorana Christea (ROU) 7-6 (7/3), 6-1
Zhang Kailin (CHN) bt Jana Cepelova (SVK x7) 6-1, 6-4
Wang Yafan (CHN) bt Samantha Stoser (AUS x1) 2-6, 6-2, 6-2
Monica Puig (PUR) bt Karin Knapp (ITA) 6-1, 4-6, 6-2
Monica Niculescu (ROU) bt Bojana Jovanovski (SRB x4) 6-2, 6-2
Silvia Soler-Espinosa (ESP) bt Sloane Stephens (USA x3) 6-3, 4-6, 6-4