Sydney McLaughlin set a world record in the women's 400m hurdles at the US Olympic trials on Sunday, clocking 51.90sec after a thrilling battle with rival Dalilah Muhammad.
The 21-year-old star became the first woman ever to duck below the 52-second barrier after running a superb tactical race against reigning Olympic and world champion Muhammad.
Muhammad, who had held the previous world record of 52.16sec following her win over McLaughlin at the 2019 World Championships in Doha, was second in 52.42sec.
It was another classic duel between McLaughlin and Muhammad, who have dominated the 400m hurdles in recent seasons.
The thriller at Hayward Field took place after a delay of several hours as a record heatwave which roasted Eugene in triple-digit temperatures forced the afternoon finals to be moved to the evening.
The delay did not appear to have adversely impacted either McLaughlin or Muhammad, who quickly moved away from the rest of the field after going out fast.
Muhammad, whose pre-season was disrupted after contracting Covid-19 earlier this year, had a slight lead off the final bend.
But the 2016 Olympic champion was unable to respond when McLaughlin kicked hard in the home straight, the youngster powering over the line and then clutching her face in shock as her record time was confirmed.