Jerome Young posted a season's best time to win the men's 400 metres at the World Athletics Championship at the Stade de France in Paris on Tuesday.
The Jamaican-born sprinter, who became a US citizen in 1995, got of the blocks quickly and finished the one-lap race in 44.50 seconds.
His team mate, Tyree Washington, was second in 44.77 seconds while Mac Raquil of France clocked a national best of 44.79 seconds to finish third.