Justin Gatlin of the US proved he will be the toughest rival for Jamaican sprinter Usain Bolt at next month's world championships by running 9.94 seconds to win the 100 metres at the Herculis meeting in Monaco.
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 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 US team to victory in the 4x100 relay with a time of 37.58 before winning the 100.
"It was my first race back from injury. So it felt good to go out there," Gatlin said. "With my injury, it hindered me from training the way I need to train to beat the times I need to beat. So I have a couple more weeks to get ready."
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 of a positive test for a banned substance.
Gatlin is the only sprinter who has beaten Bolt this year.