World number five and French Open winner Li Na became the sole seed casualty in the opening round of the China Open on Sunday, slumping to a 6-4, 6-0 defeat to the unknown Romanian qualifier Monica Niculescu.

Li Na of China attends the press conference after the first round of women's singles against Monica Niculescu of Romania at 2011 China Open Tennis Tournament in Beijing, China Oct. 2, 2011. Li Na Lost 4-6, 0-6. [Wang Lili/Xinhua]

Samantha Stosur from Australia will benefit a lot through Li's defeat as the newly crowned U.S. Open champion was heading to a possible fourth round clash against the home favored player, but now the world number six stays much more comfortable in her zone.

Unlike her major competitor Li, the Australian was in a class of her own in the first round clash,needing only one hour and 10 minutes to send her opponent Tsvetana Pironkova from Bulgaria packing at 6-4, 6-0.

Stosur, who also enjoyed the best season of career this year, was hardly troubled by her underdog rival. It was close in the opening set, but the second set was a lopsided one where the Australian took all her opponent's service games and allowed the Bulgarian to score only seven points.

In the most absorbing match of the second matchday held in the newly built 15,000-seat National Tennis Stadium, Niculescu did not have stage fright but the 29-year-old Li looked shaky.

"I can say that I am a little bit surprised to beat her, but I really thought I play good. My tactics worked, I play long balls and mixed it with net approach," the 24-year-old Niculescu said.

The second set of the featured match proved a torture for the crowd standing in the cold and Li herself, the first Chinese to win a Grand Slam trophy. She was horribly out-of-form and her game become ugly with comitting many grave mistakes andlooking like she never wanted to win. In the most humiliating way of losing a match, Li dropped the set at love.

"Right now I just lose all the confidence. On the court I don't know what I can do. I was feeling that winning even one point is tough for me," said a disappointed Li, "if the player has noconfidence, naturally you will lose the match."

"I think it's end of the season, so it's long break for me, like not only for the body, but alsofor the mind. I think that was more important. So hopefully I can stand up again and prepare for next year."

For Li, the priority must be given to the coaching problem as she broke up with her Danish coach Michael Mortenson, who helped her bring the French Open honor. She rehired her husband coach Jiang Shan again, but obviously it did no good to her game.

"I tried to ask the coach, I know he speaks exactly what's right, but I couldn't do it."

"Anyway the match is over, so I have to look forward. It's not easy for me, but if I want to do well in the whole career I have to do it," Li added.

Elsewhere, former Wimbledon runner-up Marion Bartoli of France overcame an early scare to beat Iveta Benesova from Czech Republic 3-6, 6-4, 7-5 while the former world number one Ana Ivanovic of Serbia did not fire on all cylinders before easingpast Japanese Kimiko Date-Krumm 6-1, 6-1.

Sunday's winners also included 13th seed Anastasia Pavlyuchenkova of Russia, Gemany's 14th seed Sabine Lisicki, Slovakians Dominika Cibulkovaand Daniela Hantuchova and Spaniard Maria Jose Martinez Sanchez.