China's Liu Xiang put himself in pole position for the Olympic 110 metre hurdles as he beat the world outdoor and indoor champions with a season-leading 12.97 seconds at the Shanghai Diamond League meeting.
On a wet track, the Athens 2004 gold-medallist won it comfortably from America's David Oliver and world outdoor champion Jason Richardson.
In other results, Jamaican Olympic champion Veronica Campbell-Brown beat America's Carmelita Jeter in the women's 100 metres, while former world record-holder Asafa Powell raised his hopes for London by winning the men's 100m in 10.02 seconds.
Powell, beaten by a resurgent Justin Gatlin in this month's opening Diamond League meeting in Doha, timed six hundredths of a second quicker than America's Michael Rodgers, who was recently hit with a nine-month, retroactive drug ban.
Ethiopian distance legend Kenenisa Bekele also had an evening to forget as the Olympic champion finished fifth in the men's 5,000, nearly four seconds behind the winner, fellow Ethiopian Hagos Gebrhiwet, who timed 13min 11.00 seconds.