TOKYO (AFP) World silver medallist Wang Xin of China opened her title challenge at the Japan Open with an easy win over Taiwans Pai Hsiao-ma on Wednesday. Fresh from her victory at the China Masters last weekend, the Chinese second seed coasted to a straightforward 21-16, 21-14 win in 29 minutes in the first round of the womens singles. The world number two rated her performance as 70 percent, adding: I feel relaxed on court. Thats why I can play calmly. Wang Xin, runner-up to Chinese world number one Wang Yihan at last years Japan Open, lost to her compatriot Wang Lin in the world championship final last month. She faces severe competition from her compatriots as the players eye the London Olympics in 2012. Wang Yihan has not been playing very well recently. Shes been trying to regain her best form. But Im sure she is getting back soon. Both (Wang Yihan and Wang Lin) are my biggest rivals for the Olympics. Top seed Wang Yihan will play Jeanine Cicognini of Switzerland later in the day. Fourth seed Tine Baun of Denmark stayed on course for a potential semi-final showdown against Wang Xin by beating Salakjit Ponsana of Thailand 21-13, 21-11. I played well. It was good that my body got moving after last week and I took the right decisions. Im very happy about this victory, because Salakjit is a good player, said Baun, runner-up at the China Masters. Baun captured her first tour title at the 2007 Japan Open under the name of Rasmussen. She has also won the All England twice and the European championships this season. Chinese third seed Wang Shixian beat Megumi Taruno of Japan 21-14, 21-16, while eighth seed Yao Jie of the Netherlands became the first seed to fall, losing to Sung Ji-Hyun of South Korea 21-18, 21-15. In the mens field, defending champion Bao Chunlai of China outclassed Dionysius Hayom Rumbaka of Indonesia 21-14, 21-10 to set up a meeting with Japans Kazushi Yamada, who beat compatriot Riichi Takeshita 21-11, 21-15.