American Aries Merritt stormed to gold in the 110 metres hurdles at the London Olympics, holding off world champion Jason Richardson to cross the line in 12.92 seconds.
The 27-year-old made the most of perfect conditions on a balmy evening at the Olympic stadium to run his fifth sub-13 second time of the season.
Richardson won silver for the United States in 13.04 seconds and bronze went to Hansle Parchment who crossed the line in a Jamaican record time of 13.12.
Defending champion and world record holder Dayron Robles, who missed most of the season through injury, pulled up with what looked like a hamstring problem after the sixth hurdle.
China's former world record holder Liu Xiang, who won the title in Athens eight years ago, fell in his first-round heat after injuring his Achilles tendon.
Britain's Lawrence Clarke finished fourth.