Wimbledon champion Maria Sharapova of Russia found it difficult to reach the doubles second round at the 585,000 US dollars China Open WTA women's tennis tournament after she and partner lost on the opening round on Tuesday.

Though Sharapova and her compatriot Vera Zvonareva enjoyed a clear advantage in the first set by leading 6-1, they lost to the Japanese pair Shinobu Asagoe/Rika Fujiwara in the following sets, 3-6, 4-6.

Sun Tiantian, who won a breakthrough women's doubles title at the Athens Olympic Games with Li Ting, suffered her singles first round defeat to Sanda Mamic of Croatia 6-4, 6-2.

Sun said: "I haven't practiced for almost a month after we returned home. I felt rusty."

Another Chinese pair Zheng Jie and Yan Zi eliminated Alina Jidkova from Russia and Abigail Spears from the United States 6-3,7-6 (8-6) to reach the women's doubles second round.

Chinese former No. 1 player Li Na romped Nicole Pratt of Australia 6-3, 6-2 to enter the next round.

Sharapova and Serena Williams of the United States will show onthe singles second round on Sept. 22 after their first round byes.