Kenya's Ruth Chepngetich won the women's marathon at the World Championships as 28 of the 68 starters withdrew in grueling conditions in Doha.
In a race that started at midnight local time, Briton Charlotte Purdue was among the athletes to pull out in temperatures of 32C and with humidity reaching over 70 percent.
Chepngetich, 23, took the first gold of the championships in two hours 32 minutes 43 seconds with athletes attempting to complete six 7km loops of the Corniche in the Qatar capital.
Bahrain's defending champion Ruth Chelimo, 39, was second in 2:33.46 and Commonwealth champion Helalia Johannes of Namibia, also 39, took bronze in 2:34.15.
Organisers decided to go ahead with the event in its scheduled slot despite fears that the conditions might not be conducive for marathon running.
Ethiopia's marathon coach Haji Adillo Roba witnessed his trio of athletes stop, including Tokyo Marathon winner Ruti Aga.
"We never would have run a marathon in these conditions in our own country," he told BBC Sport during the race.
"I'll be interested to see how many finish."
Purdue, the third fastest British female marathon runner in history, withdrew after the start of the third loop.
Compatriot Tish Jones pulled out before the race with a leg injury.
The heat and humidity took its toll with Ethiopia's Ruti Aga among four athletes driven to the finish area in a kart after pulling out
Chepngetich was among a small group that included Chelimo, two-time champion Edna Kiplagat, Kenya's Visiline Chepkesho and Johannes that broke clear from the rest as early as the fifth kilometre.
Israel's European champion Lonah Chemtai Salpeter was among the pack but dropped out as the quartet stretched away from her.
It became a two-horse race between Chepngetich and Chelimo before the eventual winner surged again, this time decisively, to secure her first major championships medal.
"I was not expecting to be a medallist in such tough conditions," Chelimo told AFP.
