LaShawn Merritt claimed a surprise gold in the 400m final to lead a clean sweep of the medals for the United States.
Merritt won in 43.75 seconds, ahead of defending champion Jeremy Wariner, who faded badly in the home straight but held on for silver in 44.74 secs.
David Neville threw himself head-first across the line to finish third in 44.80 secs and edge out Christopher Brown of the Bahamas.
Britain's Martyn Rooney was back in sixth in a time of 45.12 secs.
Merritt's time was the fifth best in history and came after he totally outran the odds-on favourite Wariner.
The 22-year-old was third coming off the turn behind Neville and Wariner, but a powerful surge in the last 100m saw him ease clear of the field to win by some distance.
"LaShawn ran a better race than me," Wariner said. "I came off the turn, I felt good, but when I went for it, it wasn't there. I have to be happy with a medal."
"Jeremy was always going to bring his A game - I just had to bring my A-plus game"
Merritt dedicated the victory to his late brother Antwan - he blows a kiss to the sky before every race.
"He passed away before I started track and field," Merritt said. "He would have been proud of what I did. I asked him to guide me out there and that is what he did."
"Jeremy Wariner is a good competitor. I knew it would be hard race because Jeremy was always going to bring his A game. I just had to bring my A-plus game."
"I learned something from [Usain] Bolt in the 200m. He really opened up in the back, so I decided I would open up in the final and let it fly."
Wariner seemed to be running on empty in the closing stages, virtually jogging through the finish line.
But Neville's finish was the complete opposite as he committed himself with absolute conviction, falling to the ground after hurling himself over the line in a desperate - and ultimately successful - effort to edge out Brown.
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