The World Half Marathon champion Peres Jepchirchir staged a stunning performance to lead compatriot Brigid Kosgei to 1-2 sweep of the gold and silver in a Kenyan show of might in the road races.
Jepchirchir timed 2hr 27min 20sec for the gold while Kosgei came second 16 minutes off the pace.
USA’s Molly Seidel put up a brilliant show of resilience in the searing heat in Sapporo to claim the bronze.
Jepchirchir’s victory secured back-to-back women’s Olympic marathon titles for Kenya and now succeeds compatriot Jemima Sumgong, who won in 2016 in Rio.
Sumgong has since been banned for use of banned substances.
The 27-year-old two-time half marathon world champion beat compatriot Kosgei (2hr 27:36) whilst Seidel secured bronze in 2hr 27:46.
Organisers, wary of the hot and humid conditions, had announced on the eve of the race the start time had been brought forward an hour to 6am local time (12am Kenyan time).
However, even with that, many runners failed to last the distance, including Kenya’s world champion Ruth Chepngetich. Other runners crossed the finish line clearly in distress, including Mexico’s Ursula Sanchez.
She staggered over the line and was attended to by a race official.
Chepng’etich fell off the pace after the 30km mark before dropping off the race.
Two hours into the race the temperature had risen to 30.6°C (87 degrees Fahrenheit) and 62.7% humidity.
Jepchirchir and Kosgei had moved up a gear with four kilometres remaining with just a quartet of runners in contention for the medals.
Seidel was the first to be dropped followed by Kenya-born Israeli Lonah Salpeter.
The Israeli had looked set to give her adopted country their first ever athletics Olympics medal.
However, her hopes of a bronze were brought to a brutal end as she pulled up after being dropped leaving Seidel clear in third spot.
Up ahead Jepchirchir made her decisive move for gold with two kilometres remaining and Kosgei could find no reserves in her tank.
It was the first defeat for Kosgei in five marathons — she won Chicago (2018/19) and London (2019/20) — but she had been struggling for a while in the hot conditions even resorting to stuffing an ice pack down the front of her running vest.
However, it was all smiles at the finish — a mixture of joy and relief the endurance test was over — as Kosgei embraced the new champion.