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.

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