Tyson Gay beat Usain Bolt in the 100 meters at the DN Galan meet in 9.84 seconds at the same stadium where Bolt last lost a race two years ago.
The American always looked in complete control against world record-holder Bolt, who was second in 9.97 on Friday.
A sellout crowd in the 1912 Olympic Stadium was silent before the race between the two fastest men of all time. And the tension increased among the 20,000 spectators even further after two false starts.
The pair raced side by side in lanes four and five and Gay looked comfortable throughout, slowly pulling away while the Jamaican was straining to keep up in the highly anticipated race.
"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.
"My body worked well today, I was excited and motivated."
Bolt has ran faster this year, timing 9.82 a month ago in Lausanne, Switzerland.
"I think (today) 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. If you don't beat me this season it's not going to happen next season because next year is a championship year."
The sprinters both looked like they left plenty in reserve when they cruised through the heats, and so it proved for Gay when it came to the final.
Richard Thompson of Trinidad finished third in 10.10.
Asafa Powell defeated Bolt at the same meet two years ago, but pulled out of this year's race on Wednesday with a back injury, denying fans the chance to see the first race between the world's three fastest men since Bolt stormed to a new world record of 9.58 last August at the world championships in Berlin.