Luke Kibet ended Kenya's 20-year wait for a men's world marathon title with a comfortable victory in the first event of the 11th world championships on Saturday.

The 24-year-old prison guard overcame searing heat and high humidity to clinch gold in two hours, 15 minutes and 59 seconds.

Kenyan-born Qatari Mubarak Hassan Shami took silver, more than a minute behind his former compatriot in 2:17:18, and Swiss Viktor Roethlin came through to finish third in 2:17:25.

"I'm happy and I am proud to win the gold medal for my country," Kibet told reporters. "It's been a long time for Kenya without the gold medal in marathon."

Kibet made his move after 90 minutes on the road, breaking free of compatriot William Kiplagat, Shami and Eritrean Yared Asmarom in the leading group.

"We were going so slow, I thought if we kept up that pace it would be a 2.20 or 2.30 time so I decided to go," Kibet added.

By the 35km mark, Kibet had opened up a 23-second lead over Shami and he loped unchallenged across the line at the Nagai stadium to become the first Kenyan man to win the world marathon title since Douglas Wakiihuri in Rome in 1987.

The field set off at 0700 local time to avoid the worst of the searing heat but the temperature climbed steadily from 28 degrees Celsius at the start and at least one competitor was taken from the course on a stretcher.

Given the conditions, it was no surprise that the leaders took more than 16 minutes to reach the 5km mark and a quick time was never a realistic prospect.

Nobody was prepared to go out on their own and the leading 25 runners were separated by less than a minute as Uganda's Alex Malinga led the field until just after the 20km mark.

Kibet, Kiplagat, Asmarom and Shami slowly pulled away but when Kibet broke clear none of his rivals was able to go with him.

Shami, formerly Richard Yatich, said he was carrying an injury and had not felt confident of winning a medal.

"When (Kibet) started to go, I felt in my legs that I could not match him," he said. "In the end, the legs were just not moving."

Japan [Images] retained the World Marathon Cup title, in which the rankings are decided by the combined times of the top three finishers from each country.

Tsuyoshi Ogata, Satoshi Osaki and Toshinara Suwa finished fifth, sixth and seventh to clinch the cup for the hosts.