MONACO (AP) -- Justin Gatlin of the United States proved that he will be the toughest rival for Jamaican sprinter Usain Bolt at the world championships by running 9.94 seconds to win the 100 meters at the Herculis meeting on Friday.
Gatlin held off a challenge from fellow countryman Dentarius Locke, who finished 0.02 seconds back. French champion Jimmy Vicaut took third in 9.99.
Amantle Montsho of Botswana, Vitezslav Vesely of the Czech Republic, along with Kenyans Asbel Kiprop and Edwin Cheruiyot Soi meanwhile set world-leading marks in the 10th leg of the Diamond League circuit.
World champion Montsho ran the women's fastest 400 this season in 49.33. European champion Vesely threw 87.68 in the men's javelin. Kiprop clocked 3:27.72 to beat Mo Farah of Britain in the men's 1,500. And Soi ran 12:51.34 in the men's 5,000.
In his first competition back from a hamstring injury, Gatlin had enough power to lead a U.S. team to victory in the 400 relay with a time of 37.58 before winning the 100.
Gatlin was not disappointed by his time, 0.19 second shy of American sprinter Tyson Gay's world-leading time.
Gay pulled out from the Herculis meet and the worlds after being notified last week by the U.S. Anti-Doping Agency of a positive test for a banned substance.
Gatlin is the only sprinter who has beaten Bolt this year. The 2004 Olympic champion and 2005 world champion edged Bolt by 0.01 second in Rome last month.
World champion Kiprop entered the final lap of the 1,500 with the lead and broke away in the final curve.
Farah came second in 3:28.81 to break the European record previously held by Spaniard Fermin Camacho since 1997. Britain's 5,000 and 10,000 Olympic champion from the London Games was running his first 1,500 this season to work on his speed ahead of the worlds.
Olympic runner-up Leonel Manzano of the United States finished a distant 13th, more than 16 seconds off the pace.
Montsho beat Stephanie McPherson by 0.59 second to take the women's 400 and leapfrog Antonina Krivoshapka for the world-leading time. Francena McCorory of the United States ran a personal best in 49.96 to finish third.
Vesely outclassed his rivals in the javelin, with Dmitriy Tarabin of Russia throwing 84.33 to finish second. Former Olympic champion Andreas Thorkildsen of Norway completed the podium with a 83.71 mark.
In the women's 100 hurdles, Sally Pearson of Australia is still short of fitness three weeks before the worlds. The Olympic and world champion wound up fifth in a race won by Queen Harrison of the United States in 12.64. Pearson had a season hampered by a hamstring injury, losing also in Birmingham, Lausanne (Switzerland) and Sotteville (France).
Jehue Gordon of Trinidad and Tobago won the 400 hurdles by stunning Olympic champion Felix Sanchez of the Dominican Republic and former world champion Kerron Clement of the United States.
Gordon ran 48.00, just 0.04 shy of the world-leading time set by Olympic runner-up Michael Tinsley at the U.S. trials last month. Sanchez and Clement finished respectively sixth and seventh.
Brigetta Barrett leaped 2.01 in the women's high jump to beat by three centimeters Olympic champion Anna Chicherova of Russia and two-time world champion Blanka Vlasic of Croatia.