GUANGZHOU: Four of the top five seeds including No.1 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 No.4 in the rankings.

But she is now at 20 after failing to get past the semifinals of any of the 18 tournaments she has competed in so far this year.

Radwanska off the mark

In Seoul top seed Agnieszka Radwanska hammered Polona Hercog Tuesday as she set out on a quest to successfully defend a title for the first time at the WTA Korea Open.

The Polish world No.5, returning to action after her US Open second-round defeat to China’s Peng Shuai, won 6-3, 6-3 to get her title defense off the mark.

Former Seoul champion Maria Kirilenko, playing on a wildcard after missing three months of the season with a knee injury, beat Croatia’s Donna Vekic 3-6, 6-2, 6-4 to reach round two.

“It was a tough time after my injury last year. I haven’t played much this year and after Wimbledon it got worse so I couldn’t play much of the summer either,” said the Russian.

“I really missed playing and I’m happy I could win this match today, because it was my first long match so far this year,” added Kirilenko, who lifted the trophy in 2008.

Hingis, Bencic debut

In Tokyo, Former world No.1 Martina Hingis and rising star Belinda Bencic made their debut as a dream doubles team for Switzerland Tuesday, winning their first match together at the Pan Pacific Open.

Four-time Grand Slam singles champion Hingis, 33, and 17-year-old Bencic, who reached the US Open quarterfinals two weeks ago, combined to oust Rika Fujiwara of Japan and Taiwan’s Hsieh Shu-Ying 6-4, 6-2 in the first round.

The all-Swiss pairing was announced as a wild card only last week after Hingis’s usual partner Flavia Pennetta of Italy pulled out of the $1 million tournament with a right-foot injury.

With Pennetta, Hingis reached the US Open final but her bid for a 10th major doubles title was denied by the Russian pairing of Ekaterina Makarova and Elena Vesnina.

Hingis, whose mother Melanie Molitor has trained Bencic for 10 years along with the youngster’s father Ivan, said she was committed to play with Pennetta at least until the end of this year. But a regular pairing with Bencic may be possible in the future.

In the singles first round, sixth-seeded Dominika Cibulkova of Slovakia beat Belgian Kirsten Flipkens 6-1, 6-3 and eighth-seeded Carla Suarez of Spain outlasted Japan’s Kurumi Nara 6-1, 2-6, 6-2.

The top four seeds, including world No. eight Angelique Kerber of Germany and eighth-ranked and US Open finalist Caroline Wozniacki of Denmark, took a bye into the second round.