Kenyan Amos Kipruto marked his London Marathon debut with a decisive victory on Sunday as Ethiopian 23-year-old Yalemzerf Yehualaw became the youngest winner of the women's race.

It was a maiden London victory for Yehualaw in what was just the second marathon of her career.

The 30-year-old Kipruto, a world bronze medallist in Doha in 2019, crossed the line in London in two hours, four minutes and 39 seconds after breaking away late on.

Leul Gebresilase of Ethiopia finished second in 2:05:12, with Bashir Abdi of Belgium third in 2:05:19.

Ethiopian distance great Kenenisa Bekele was fifth with compatriot Sisay Lemma, last year's London Marathon winner, seventh.

Kipruto, understandably elated by his victory, said: "This is my London debut and it's a wonderful day.

"I'm very, very happy I won, but I can't explain how I won. I decided to make a decisive break because of my training – I was confident and I knew when to go."

Yehualaw's winning time of 2:17:26 was just three seconds outside the personal best she set at Hamburg in April when making the fastest debut in any women's marathon.

Her time was also the third fastest in the history of the women's London Marathon.

Defending London champion Joyciline Jepkosgei was second, the Kenyan finishing in 2:18:07, with Ethiopia's Alemu Megertu third in 2:18:32.

Yehualaw's victory was all the more impressive as she appeared to trip on a speed bump with six miles to go.

Nevertheless, the women's 10 kilometre world-record holder recovered to rejoin the leading pack.

Yehualaw surged clear with four miles to go and Jepkosgei was unable to reel her in.

Yehualaw's breakaway included an astounding 4:43 mile split in the 24th mile.

It appeared the world record for a women's-only marathon of 2:17:01 was under threat, but Yehualaw was happy just finishing first.

"I really like this race," she said. "I knew it was fast paced and I was aware we were on world record-breaking time at one point, but I just focused on running as fast as I could."

Several leading runners were ruled out of this year's race in London through injury, including British hope Mo Farah, while four-time winner Eliud Kipchoge of Kenya opted against competing after smashing his own world record by half a minute in last week's Berlin Marathon in a time of 2:01:09.

"Kipchoge is an inspiration for us all and he is a legend for the young generation in Kenya," said Kipruto.

"He is another level in sport and has been a mentor to me. I really wish to follow in his footsteps. I'm so proud to be here."

The women's race was without world record-holder Brigid Koskei, the 2021 and 2021 champion. The Kenyan withdrew because of a hamstring injury.

There was a Swiss double in the wheelchair competition on Sunday as Marcel Hug and Catherine Debrunner set new London course records in the men's and women's races respectively.

Hug retained his London crown in 1:24:38 after winning a sprint finish against Daniel Romanchuk of the United States.

Britain's David Weir, competing in his 23rd London Marathon, was third.

Debrunner crossed the line first in a time of 1:38:24 after winning her maiden marathon in Berlin a week ago. (AFP)