French swimmer Florent Manaudou shot to the Olympic 50 metres freestyle gold, consigning defending champion Cesar Cielo to his first major final defeat in four years.
Manaudou won in 21.34 seconds, with American Cullen Jones taking the silver two tenths of a second slower on Friday.
World record holder Cesar Cielo took bronze in 21.59, tapping home just five hundredths of a second behind Jones.
Cielo has not been beaten over 50 meters since winning gold in Beijing.
Asked whether he could believe he had won the gold, the 21-year-old Manaudou, the younger brother of women's Olympic gold medallist Laure Manaudou, didn't hesitate.
"If I didn't believe it, I wouldn't be in an Olympic final. I was very relaxed. I think it's the secret, being relaxed," he said.
He admitted, however, that he wasn't sure he had the gold in the bag when he touched home.
"I didn't know. In the 50m it's very quick, you don't look. I saw the light come on. I knew I was going to be on the podium, which was great, but I didn't know I would be first."