Wayde van Niekerk has broken Michael Johnson's long-standing 400m world record to win Olympic gold.
The South African, who had been drawn in lane eight, produced one of the most memorable displays in the history of the sport as he clocked 43.03s.
Before the race, Kirani James and Lashawn Merritt had been tipped to do battle for gold but they were left in Van Niekerk's shadow as he went out hard over the first 200 metres.
His rivals would have expected him to tire during the closing stages but he only increased speed to break Johnson's best time of 43.18s, which had stood for 17 years.
James and Merritt came home in times of 43.76s and 43.85s respectively while Great Britain's Matthew Hudson-Smith was eighth in 44.61s.