The runner crossed the line more than 1.20 seconds clear of her nearest rival. Photograph: (Getty)
The South African has been dogged by several controversies because of her naturally high testosterone levels
Controversial South African runner Caster Semenya produced a devastating sprint finish to claim the Olympic 800m crown, four years after being denied gold by Russian dope cheat Mariya Savinova.
The 25-year-old 2012 silver medallist turned on the gas with 150m to go, crossing the line more than 1.20sec clear in 1min 55.28sec at the Olympic Stadium.
Francine Niyonsaba of Burundi took silver in 1:56.49 with Kenya's Margaret Wambui claiming bronze in 1:56.89.
"I used to be a sprinter, I ran the 100m, 200m in high school," Semenya said of her finish.
"It was just a fantastic race. Obviously, there can only be one winner and it turned out good for me. It wasn't about running fast, it was about running a good race."
Semenya has been at the centre of a raging controversy in recent years because of her naturally occurring condition, hyperandrogenism, which causes elevated testosterone levels.
Rival runners have said they want authorities to revisit rules that limit the amount of testosterone allowed in competitors.
Partially in response to those rumblings, world athletics chiefs implemented restrictions on testosterone levels in 2011.
Following the introduction of those rules, Semenya's times slipped, with many assuming she was taking medication to keep her testosterone levels within acceptable limits.
She was still good enough to take silver behind Savinova in London however. The Russian is facing a lifetime ban from the sport after evidence implicating her in doping.
And when the Court of Arbitration for Sport ruled the International Association of Athletics Federations (IAAF) restrictions illegal, Semenya was free to compete in her natural state.
Hours before Saturday's final, IAAF chief Sebastian Coe indicated the world body would seek to revisit the issue in future.
Semenya however would not be drawn on the issue.
"Tonight is all about performances," she said. "We're not here to talk about the IAAF. We're not here to talk about speculations.
"We're here to talk about the 800m that we ran today."
Semenya never looked in trouble in Saturday's final, biding her time after a 57.59sec opening lap.
Niyonsaba hit the front with around 300m to go but Semenya was always within striking distance.
With 150m left she made her move, calmly accelerating clear to take the lead as the race for silver and bronze unfolded behind her.
Canada's Melissa Bishop dug deep in the home stretch but was just pipped for bronze by Wambui.