Sydney McLaughlin shaved almost half a second off her own world record as she came from behind to win the women's 400m hurdles at Tokyo 2020 on Wednesday.
The American followed up Karsten Warholm's world record feats in the men's equivalent event on Tuesday, with a time of 51.46.
McLaughlin eclipsed her previous mark of 51.90, set in June earlier this year at the USA Olympic trials in Eugene.
USA's Dalilah Muhammad also broke the previous world record mark, claiming silver with a personal best 51.58.
Muhammad set the early pace but McLaughlin mowed her down over the final 100m to claim victory.
Femke Bol, from the Netherlands, won the bronze medal with a European record time of 52.03.
The top three all beat the previous Olympic record of 52.64, set by Jamaica's Melaine Walker at Beijing 2008.
The top five fastest times in women's 400m hurdles history:— AW (@AthleticsWeekly) August 4, 2021
1⃣ Sydney McLaughlin (2021)
2⃣ Dalilah Muhammad (2021)
3⃣ Sydney McLaughlin (2021)
4⃣ Femke Bol (2021)
5⃣ Dalilah Muhammad (2019) #Athletics #Olympics pic.twitter.com/nIs69K2p40
Jamaica's Janieve Russell was fourth with Ukrainian pair Anna Ryzhykova and Viktoriya Tkachuk unable to threaten from the inside lanes, to finish fifth and sixth respectively.