South Africa's Caster Semeya has won the second women's 800m semi-final this evening.
The 21-year-old positioned herself in the midfield before kicking towards the front with 200m to go and recording a season-best time of 1:57.67.
Kenya's Janeth Jepkosgei Busienei led for the majority of the race but was eventually overtaken by both Semenya and the European champion Elena Arzhakova of Russia.
Semenya and Arzhakova earn automatic qualification for Saturday's final, while Busienei and America's Alysia Johnson Montano, who finished fourth, currently occupy the two fastest-loser qualification berths.
