American Sydney McLaughlin-Levrone obliterated her own 400-meter hurdles world record with a time of 50.37 seconds to retain her Olympic title on Thursday.
Anna Cockrell of the United States took silver and Dutchwoman Femke Bol claimed bronze.
McLaughlin-Levrone lowered her previous mark of 50.65 set at the US trials in June.
It was the sixth time she had broken the record and the crowd at the Stade de France went into a frenzy when it became clear a new all-time best was within her reach.