GUANGZHOU, China (AP)—Top-seeded Samantha Stosur was the most notable among the five seeds to lose in first-round action at the Guangzhou Open on Tuesday.

The 2011 U.S. Open champion fell to Chinese wild card Wang Yafan 2-6, 6-2, 6-2. Stosur won only two of her 11 break points, while Wang, ranked 251st, 231 spots below Stosur, took four of her six chances.

Also ousted were No. 3 Sloane Stephens of the U.S., No. 4 Bojana Jovanovski of Serbia, No. 5 Zarina Diyas of Kazakhstan for the first time in three matches against 220th-ranked qualifier Zhang Ling of Hong Kong, and No. 7 Jana Cepelova of Slovakia, to 259th-ranked qualifier Zhang Kai-Lin of China.

Of the tournament's eight seeds, only No. 2 Alize Cornet of France, a winner on Monday, advanced to the second round.

Also, Karin Knapp of Italy, who won her first WTA title in Tashkent on Saturday, was beaten by Monica Puig of Puerto Rico 6-1, 4-6, 6-2, and 2012 champion Su-Wei Hsieh of Taiwan won her opener.