Ethiopia's Genzebe Dibaba produced a stunning run in Friday's Monaco Diamond League meeting to set a 1500m world record of three minutes 50.08 seconds.
The 24-year-old took four seconds off her personal best to break Chinese athlete Yunxia Qu's record of 3:50.46, which had stood since September 1993.
Dibaba may not compete at the distance at next month's World Championships, having specialised in 5,000m recently.
"I'm very happy the time is so fast, very happy with this record," she said.
"Finally all of this preparation is paying off."
Dibaba, younger sister of three-time Olympic champion Tirunesh Dibaba, already held the 1500m indoor record, and broke three world bests in 15 days last year. But she is still waiting for her first major championship medal.
Her previous outdoor best had been set in Barcelona just last week, and was already the year's world-leading time.
"With the training I did in Barcelona, I knew I was going to break the record," Dibaba added, speaking through a translator.
Britain's Laura Muir finished fifth, breaking her own Scottish record in 3:58.66. Only 2004 Olympic champion Dame Kelly Holmes has run faster among Britons.
On a night of fast races, Asbel Kiprop's winning time in the men's 1500m was the fifth fastest ever.
The 26-year-old Kenyan won in a time of 3:26.69 seconds, making him the third fastest athlete over the distance.
Britain's Mo Farah ran within a tenth of a second of his personal best to finish fourth.