Beijing half-marathon organisers said Monday they were investigating after footage shared widely online appeared to show three African runners deliberately allowing China's He Jie to win.
Video clips of Sunday's race showed the Kenyans Robert Keter and Willy Mnangat, Dejene Hailu of Ethiopia and home runner He approaching the finish.
The three African runners can be seen pointing to the finish line and apparently waving He out in front, while appearing to slow down.
He, the 2023 Asian Games marathon gold medallist, won by one second.
The four had stuck together throughout the course of just over 13 miles (21 kilometres), a broadcaster noted.
"We are investigating and will announce the results to the public once they are available," a person from the Beijing Sports Bureau, who wished to remain anonymous, told AFP.
The event's organiser - the Beijing Sports Competition Management and International Exchange Center - also said an investigation had been launched.
The incident received significant attention on Chinese social media site Weibo, with some users criticising what they saw as an "embarrassing" result.
"This will certainly be the most embarrassing championship in He Jie's career," one wrote.
"With such a major organiser and such a well-known event, this really pushes sportsmanship to the ground in shame," the post added.
Long-distance running has boomed in recent years among China's middle class, but there have been numerous instances of cheating and poor organisation.
In 2018, at a half-marathon in the southern city of Shenzhen, 258 runners were found to have cheated, including many who took shortcuts.
Traffic cameras caught them darting through trees to join a different part of the race.
In 2019 a woman was filmed riding a green-coloured rental bike in the Xuzhou International Marathon in eastern China.
She was ordered by race officials to dismount the bike, only to get back on again afterwards.
AFP