Shanghai, May 20 (IANS): Chinese star hurdler Liu Xiang is back at the top with an overwhelming victory, leaving behind three world class American hurdlers at the 2012 Diamond League Shanghai.

The 28-year-old Athens Olympic champion clocked 12.97 seconds Saturday to claim the men's 110m hurdles, bettering the season's best of 13.03s set by America's Aries Merritt two weeks ago.

David Oliver of the United States finished second in 13.13s while another American Jason Richardson, newly crowned world champion in Dague last year, settled for third in 13.16. Merritt was fourth in 13.26, reports Xinhua.

"I am always very confident," said Liu. "But I want to say thanks to my rivals, because without their stimulus I couldn't have run within 13s. I have not expected to run this fast, so I am very happy.

"I performed well from the start to finish," added Liu, whose strategy was seven steps to the first hurdle.

"Although it was a rainy day, I gave my full play," said the winner. "I never hold back but just deliver all I have."

Liu said 12.97s was impressive but he never thought about how fast he could run in the London Olympics or breaking the world record.

"No matter whether I am on my top form or not, I have never thought about breaking the world record," said Liu, who clocked in 12.88 to set a world record in Switzerland in 2006.

"To break the world record is everyone's dream, but it's so hard to achieve it. I performed perfect today and to keep the best form and stand on the Olympic field is my aim."

Also Saturday, former world record holder Asafa Powell of Jamaica won the men's 100m in 10.02 seconds.

Besides Liu's 12.97, another three world best results this year were set here in Shanghai.

Ethiopian Genzebe Dibaba won the women's 1,500m in a world best 3:57.77, while Kenya's Milcah Chemos won the women's 3,000m steeplechase in 9:15.81. Hagos Gebrhiwet of Ethiopia claimed the men's 5,000m title in 13:11.00, which was also the world fastest so far this year.

Jamaican Asafa Powell recovered from his loss to American Justin Gatlin last week to storm to victory in the 100m, adds CMC.

Gearing up for what will be a critical Olympic season, Powell clocked 10.02 seconds at the Shanghai Stadium to grab a confidence-boosting win.

He was second to Gatlin in the Diamond League opener in Doha last week.

Running out of lane five, the 29-year-old Powell burst from the blocks and had established a solid advantage after 50 metres.

Fellow Jamaican Nesta Carter chased from lane six but faded to finish third as American Michael Rodgers closed quickly to finish second in 10.08 seconds. Carter was timed at 10.16.

World record holder Usain Bolt chose to skip the tournament.

There were also victories for Jamaicans Veronica Campbell-Brown in the 200 metres and Novlene Williams-Mills in the 400m.

Campbell-Brown, the reigning Olympic and World 200 metres champion, also had a good start and was first out of the curve.

American Carmelita Jeter, the 100m World champion, came to challenge but Campbell-Brown pulled away to cross the line first in 22.50 seconds.

Jeter, who stumbled metres from the finish, was timed at 22.62.

Williams-Mills, meanwhile, posted 50 seconds flat to win her event.