Canada's Melissa Bishop finished fourth in the 800m final Saturday night, just failing to hold on to the bronze-medal position she held as the runners hit the final straightaway.
It was Margaret Wambui of Kenya who overtook Bishop, crossing the line 0.13 seconds faster than the Canadian.
Bishop broke her own national record in defeat with a time of 1:57.02.
South Africa's Caster Semenya won gold, and Franchine Niyonsaba of Burundi the silver.