US racer Sydney McLaughlin smashes her own world record to clinch 400m hurdles gold medal

The 21-year-old clocked 51.46 seconds having previously set a world best of 51.90 seconds to become the first woman to break the 51-second barrier.

McLaughlin powered through in the last 20 metres to take the title and beat defending champion Muhammad having been third on the final bend.

It came after the men’s 400m hurdles on Tuesday – already labelled one of the greatest races – when Karsten Warholm broke his own world record to win in 45.94s.

He took almost a second off his previous world best of 46.70s he set in Oslo.

The USA’s Rai Benjamin (46.17s) was second with Brazil’s Alison Dos Santos (46.72s) third – with both coming inside Kevin Young’s long-standing previous world record of 46.78s the American set 29 years ago.