At that, world leader Francine Niyonsaba, returning medalists Caster Semenya and Janeth Jepkosgei were all missing.

In the final Alysia Montaño displayed tactics reminiscent of Johnny Gray, taking the race out in 26.80 and 56.06 splits opening up as much as a 15-meter lead on the field.

Sum had spent most of the last lap second to Montaño, but when defending champion Mariya Savinova tried to go past her at the head of the straight, she responded and held off the challenge.

In 2015, Savinova and Ekaterina Poistogova were recommended for lifetime bans dating back to the 2012 Olympics as part of the wholesale Russian performance-enhancing drug scandal.

On 10 February 2017, the Court of Arbitration for Sport (Cas) officially disqualified Savinova's results backdated to July 2010.