Kerron Clement, of the United States, held off fast-finishing Kenyan Boniface Tumuti to win the men's Olympic 400 metres hurdles.
Running with a relaxed, easy rhythm, Clement was the clear leader going into the closing metres, but had to dip on the line to deny Tumuti as the Kenyan came up fast on the outside, with Turkey's Yasmani Copello taking bronze.
It was Clement's first major championship medal since he won the 2009 world title, having taken the silver at the Beijing Olympics the year before.
Javier Culson of Puerto Rico was disqualified for a false start and sat sobbing by the side of the track before trudging away.