The women’s title at the 127th running of the world's oldest marathon also went to Kenya as double Olympic 5,000 metres silver medallist Hellen Obiri, in only her second marathon, won in a personal best of 2:21:38.

Kipchoge, 38, whose ambition is to become the first runner to win all six annual World Marathon Majors, had hoped to tick Boston off his list after victories in London, Berlin, Tokyo and Chicago, leaving only the New York City to be attempted.

But, on the tenth anniversary of the Boston Marathon bombing which killed three people and injured hundreds, Kipchoge dropped out of contention around the 20-mile mark on Heartbreak Hill, after missing a drinks station at 19 miles, and eventually finishing sixth in 2:09:23.

At the halfway point it had all looked very different, with Kipchoge in command of the lead group and on 2:04 pace.

It was only the third defeat in 18 marathons for the man who set an official world record of 2:01:09 in Berlin last year and is the first man to have covered the distance in less than two hours.

Chebet, 34, who moved clear of the lead pack over the final six miles of a challenging and hilly course, clocked the third fastest in the history of the race to become the first man to retain the title since 2008.

Tanzania’s Gabriel Geay was second in 2:06:04, with Chebet’s training partner and compatriot Benson Kipruto third in 2:06:06.

Fourth place went to Kenya’s Albert Korir in 2:08:01, ahead of Morocco’s Zouhair Talbi, who finished in 2:08:35.

“Eliud was not so much of a threat,” Chebet said through a translator, adding that he had kept his options open until the final 12km of the race and been ready to cover any move.

 “Bottom line is, we had trained well. Our confidence in the quality of training made us feel good in taking on the race.”

Kipchoge, who had not reported any problems before the race, did not speak to the media after, instead releasing the following statement:

"I live for the moments where I get to challenge the limits.

"It’s never guaranteed, it’s never easy. 

"Today was a tough day for me. 

"I pushed myself as hard as I could but sometimes, we must accept that today wasn’t the day to push the barrier to a greater height. 

"I want to congratulate my competitors and thank everyone in Boston and from home for the incredible support I am so humbled to receive. 

"In sports, you win and you lose and there is always tomorrow to set a new challenge.

"Excited for what’s ahead."

Obiri, 33, who won the world 5,000m title in 2017, finished 12 seconds clear after putting in a final surge with a kilometre remaining to move away from Ethiopia’s Amane Beriso, whose presence at her heels was clearly giving her cause for unhappiness.

Beriso - race favourite after taking six minutes off her personal best at the Valencia Marathon in December to win in 2:14:58, the third fastest time in history - was second in 2:21:50.

Third place went to Israel’s 34-year-old world bronze medallist and 2018 European 10,000m champion Lonah Salpeter in 2:21:57.

Ethiopia’s Ababel Yeshaneh was fourth in 2:22:00 despite a heavy fall on mile 24 and Emma Bates of the United States finished fifth in 2:22:10.

Obiri, who won world 1500m bronze in 2013, said she was unwilling to push the pace earlier in the race.

“I can’t do it in front,” she said.

“I have to wait, wait.”

She added that having her daughter, Tania, and her husband, Tom Nyaundi at the finish helped motivate her.

“I say let me work hard because my daughter is here.

“Can I try to make them happy?”

Both the men's and women's winners received $150,000 (£121,000/€136,000).

Switzerland’s double Paralympic champion Marcel Hug broke the men’s wheelchair race record with a time of 1:17:06, finishing more than 10 minutes clear of 24-year-old home athlete Daniel Romanchuk, the 2019 Boston winner, who clocked 1:27:45.

Jetze Plat of The Netherlands was third in 1:28:35.

There was a home winner in the women’s wheelchair race, where Suzannah Scaroni finished in 1:41:45 to beat Australia’s Tokyo 2020 and Birmingham 2022 champion Madison de Rozario, who recorded 1:46:55.

Third place went to Japan’s Wakako Tsuchida in 1:47:04.

The race marks the start of a busy period for major marathon races, with the annual race in London due to take place next Sunday (April 23).