Xie Xingfang of China defeated Germany's Xu Huaiwen in straight sets on Wednesday to advance to the semifinals in women's singles at the Olympic badminton tournament. In her toughest test of the tournament so far, top-seeded Xie downed seventh-seeded Xu 21-19, 22-20 to set up a semifinal showdown with compatriot Lu Lan. Xu desperately tried to force a third game by tying the second game 20-all but Xie sent a smash down the line for match point and then won with a drop shot that Xu couldn't reach. Xie's win ensured China of at least a silver medal as Friday's semifinals will feature three Chinese players. Defending Olympic champion Zhang Ning of China will face Indonesia's Maria Kristin Yulianti in the other semifinal. Lu defeated Malaysia's Wong Mew Choo after a marathon second game that went to 29 points. Lu, who is third-seeded, defeated Wong 21-7, 29-27. Eighth-seeded Wong led 20-15 in the second game but saw her lead disappear after a series of unforced errors. In an earlier match, Zhang defeated France's Pi Hongyan in three games. The second-seeded Zhang fought off a determined effort from Pi on her way to a 21-8, 19-21, 21-19 win. Indonesia's Yulianti also booked a place in the semis with a 26-28, 21-14, 21-15 win over India's Saina Nehwal. In men's doubles, Bob Malaythong and Howard Bach of the United States received a taste of China's badminton supremacy, losing to the second-seeded pair of Cai Yun and Fu Haifeng in the quarterfinals. The Chinese pair raced out to an 8-1 lead in the first game and never looked back on their way to a 21-9, 21-10 win over the unseeded Americans. “They are world-class players and we expected nothing less,” Bach said. “They converted on every opportunity they had.” Cai and Fu will meet Lee Jae-jin and Hwang Ji-man of South Korea in Friday's semifinals of men's doubles. Lee and Hwang defeated Japan's Keita Masuda and Tadashi Ohtsuka 21-12, 18-21, 21-9 in an earlier match. Rasmussen and Paaske defeated Poland's Michal Logosz and Robert Mateusiak 17-21, 21-11, 21-15 in another quarterfinal match and will meet the top-seeded pair of Markis Kido and Hendra Setiawan of Indonesia in the semis. Kido and Setiawan downed Malaysia's Koo Kien Keat and Tan Boon Heong 21-16, 21-18. In women's doubles, fourth-seeded Lee Hyo-jung and Lee Kyung-won defeated Japan's Miyuki Maeda and Satoko Suetsuna 22-20, 21-15 to advance to the finals. The South Koreans will meet second-seeded Du Jing and Yu Yang in the final on Friday.