?Liu Xiang of China competes during the men's 110m hurdles at the IAAF Diamond League athletic meeting in Shanghai, east China, May 23, 2010. Liu ranked the third with 13.40 seconds.[Xinhua/Fan Jun]

China's national hero Liu Xiang said that he is unsure about the 2012 Olympic Games after suffering another defeat at home at the IAAF Diamond League on Sunday.

The 2004 Athens Olympic champion and 2007 world titlist was beaten by American David Oliver and compatriot Shi Dongpeng in a much-anticipated race at the Shanghai Stadium.

Liu finished a disappointing third place in 13.40 seconds, behind the world indoor champion Oliver who won the race in a season best of 12.99 and Shi in 13.39.

Local fans have expected the former world record holder to regain world-class form after finishing seventh in his international return at the world indoor championships in March. He has been pinned on high hopes after the shock withdrawal from the Beijing Olympics in 2008 because of an Achilles tendon injury, which disappointed millions of Chinese fans.

Ryan Braithwaite of Barbados, the surprise winner in Berlin last year, continued his disappointing start to the season, clattering a succession of hurdles and failing to complete the race.

Liu started well but faded quickly. Oliver finished nearly five meters clear of second placed Shi as Liu completed the podium.

"I think it is a good run tonight," Liu said after the race. "I feel great even though I lost to my teammate Shi Dongpeng for the first time in my career. Shi registered a season best."

Liu said he had a fresh injury to his feet and failed to have had normal training.

"I have no reason to blame," Liu said. "I could not have intensive training. As a result I could not register good result in competition."

Liu, who jumped to fame by winning the gold medal at the 2004 Athens Olympic Games, is not confident of his future at the London Olympics.

"The London Olympics is too far for me," he said. "I must start from the very beginning. I am not sure about myself now."

Usain Bolt returned to China for the first time since his triple-gold Olympic feat, to launch his 200-meter season with a convincing win, claiming the title in a meet record in 19.76 seconds.

American duo Angelo Taylor and Ryan Bailey finished second and third with 20.34 and 20.43 seconds respectively.

"It was good, it was kind of windy. It was a good run, the feeling was was good but it was not easy. I am not in the best of shape but I enjoyed it and I looked forward to the next race," said Bolt.

Bolt, who became the first man to hold the 100 and 200m world and Olympic titles at the same time, came to the Shanghai IAAF Diamond League meet after running 9.86 secons to win his season-opening 100m at South Korea's Daegu Pre-Championships Meeting last week.

U.S. sprinter Carmelita Jeter, who ran the best women's 100m time of last year at 10.64 seconds, beat world champion Shelly-Ann Fraser of Jamaica with a time of 11.09 seconds.

Fraser finished second in 11.29 seconds and Bahamas veteran Chandra Sturrup was third in 11.38.

Fellow American Jeremy Wariner, who won three Olympic gold and one silver and five world championships medals, won the men's 400 meters in 45.41 seconds for the.

His compatriot David Neville was second in 45.70 seconds and Britain's Michael Bingham was third in 45.84.

Ethiopia's Sentayehu Ejigu clocked a personal best as she sprinted clear to win the women's 5,000m in 14.30.96 while Kenya's Augustine Choge just held off fast-finishing teammate Asbel Kiprop to win the men's 1,500m in a world-leading 3.32.20.

Australian world champion Steve Hooker looked rusty after a six week break. He failed to clear a normally routine 5.70 meters as Germany's Malte Mohr won the men's pole vault.

Australia's Fabrice Lapierre jumped a season's best 8.30m to win the men's long jump with a comfortable 12 centimeters margin over American Dwight Phillips.

The Diamond League awards points depending on performances throughout the 14-event program with the winners of the 16 meets taking home a diamond trophy and cash prize.