Dalilah Muhammad of the United States set a new world record as she powered to victory in the 400 metres hurdles at the World Championships on Friday.
Olympic champion Muhammad took gold with a time of 52.16 seconds at the Khalifa Stadium, bettering her own world record of 52.20 set at the US Trials in Iowa in July.
Sydney McLaughlin, also of the United States, took silver with a time of 52.23 while the bronze medal went to Rushell Clayton of Jamaica in a time of 53.74.
Muhammad and McLaughlin have battled across the season for dominance in the event, with McLaughlin winning the Diamond Trophy in Zurich and also scoring a victory over Muhammad in Oslo earlier this year.
But Muhammad, who had broken a 16-year-old world record with her victory at the trials in July, was in no mood to let her 20-year-old compatriot prevail on Friday.
The 29-year-old Muhammad, drawn in lane six, blazed away from the start, hurtling down the back straight at a blistering pace.
Coming off the final bend Muhammad had taken a narrow lead of a few metres and it seemed as if McLaughlin would reel her in.
But as the finish line beckoned Muhammad kicked hard and held off McLaughlin for the gold.