Faith Kipyegon kicked away from world champion Genzebe Dibaba to take the Olympic 1500 metre title in Rio on Tuesday.
World record holder Dibaba was expected to add the Olympic crown to her list of honours on day 11, but Kenyan Kipyegon had other ideas as she surged to victory in a time of four minutes and 8.92 seconds.
Dibaba was unable to respond when Kipyegon passed her at the end of the back straight and the classy Ethiopian was well back in second place, with Jennifer Simpson of the United States taking bronze.
Commonwealth champion Kipyegon, silver medallist in the World Championships in Beijing last year, ran a great tactical race and was rewarded with the most famous victory of her career.
Dibaba, troubled by injury this year, hit the front with just under two laps remaining after they went out at a pedestrian pace but was unable to get away.
Kipyegon kept with the favourite and never looked back after passing her with around 200m to go and dropped to the track after crossing the line first in a superb display of middle distance running.