Alex Bolt wins men 's 200 m gold to complete historic Olympic double . David Rudisha of Kenya breaks his own world record in the men 's 800 m . He takes gold in one minute 40.91 seconds . Will Claye finished in the silver medal position with Italy 's Fabrizio Donato taking bronze . Caster Semenya is fastest for women 's 800 m final .
Alex Bolt wins men 's 200 m gold to complete historic Olympic double . David Rudisha of Kenya breaks his own world record in the men 's 800 m . He takes gold in one minute 40.91 seconds . Caster Semenya is fastest for women 's 800 m final .