Tyson Gay beat Justin Gatlin in the 100 meters at the Diamond League Areva meet Friday, 12 days after losing to the 2004 Olympic champion in the U.S. trials.
Gay dipped across the line in 9.99 seconds, 0.04 ahead of Gatlin. European champion Christophe Lemaitre of France was third in 10.08.
Gay won three gold medals in the 2007 world championships, but has since been affected by various injuries and overtaken by Usain Bolt.
In other events, Javier Culson of Puerto Rico won the men's 400 hurdles, Kenya's David Rudisha took the 800, and Dejen Gebremeskel of Ethiopia won the 5,000 - all with world-leading times this year.
Culson finished in 47.78 seconds, and Rudisha won in 1:41.54. Gebremeskel pulled ahead of countryman Hagos Gebrehiwet in the last stretch to win in 12:46.81.
Kenenisa Bekele of Ethiopia, meanwhile, won't defend his 5,000 title at the Olympics after finishing ninth.
''I'm not that disappointed because I'll run in the 10,000,'' Bekele said. ''I wish good luck to the three Ethiopians who will be in London.''
Mariem Alaoui Selsouli of Morocco also set the world's fastest time this year to win the women's 1,500 in 3:56.15 seconds. Austria's Sally Pearson did, too, winning the 100 hurdles in 12.40.
A heavy but brief shower dampened the Stade de France track before making way for bright sunshine.
Culson had little trouble adding to his victory at the Golden Gala meet in Rome in May.
He pulled ahead at the halfway stage and held off a late challenge from world champion David Greene (47.84). Felix Sanchez finished third, with Olympic bronze medalist Bershawn Jackson fourth.
Paul Kipsiele Koech led a 1-2-3 Kenyan sweep in the men's 3,000 steeplechase.
Leevan Sands of the Bahamas comfortably won the triple jump, leaping a season-best 56 feet, 6 1/2 inches in his second attempt.
''The rain stopped at the right time for us,'' Sands said.
European pole vault champion Renaud Lavillenie of France was not at his best but did enough to win at 18-11.
Canada's Dylan Armstrong won the shot put with a mark of 67-4 3/4, taking the overall lead in the Diamond race.
''I am right where I want to be in my training,'' Armstrong said. ''Next competition is London (Crystal Palace) and then the Olympics.''
In other women's events, Murielle Ahoure of the Ivory Coast finished strongly to win the 200 in 22.55. She held off American sprinters Bianca Knight (22.64) and Charonda Williams (22.70).
Amantle Montsho of Botswana won the 400 ahead of Jamaica's Novlene Williams-Mills, with Francena McCorory of the United States in third.
Tunisia's Habiba Ghribi overtook Kenya's Lidya Chepkurui near the line to win the 3,000 steeplechase.
''I gave everything in the home straight,'' Ghribi said.
Dani Samuels of Australia won the discus with a throw of 202-9.