Gay beat the Jamaican at the DN Galan meet in 9.84 seconds at the same stadium where Bolt last lost a race two years ago.
The American seemed in complete control against the world record-holder. The pair raced side by side in lanes four and five. Gay, looking comfortable, drew away while Bolt strained to keep up and finished second in 9.97.
“I’m really happy with the win, even though Usain Bolt isn’t in the best shape,” Gay said. “It was very important to beat someone like that for the fans and the sport.”
Bolt has run faster this year, finishing in 9.82 a month ago in Lausanne, Switzerland.
A sellout crowd in the 1912 Olympic Stadium turned silent before the showdown. And the tension heightened even further after two false starts.
“I think it showed that I wasn’t in the best of shape,” Bolt said. “I’m not unbeatable. I can be beaten and it showed today.
“This is my easy season,” he added. “If you don’t beat me this season it’s not going to happen next season because next year is a championship year.”