Eliud Kipchoge broke the course record at the London Marathon, retaining his title with the second-fastest run in history over the distance as Kenya scooped an elite double.
The 31-year-old left the field trailing as he powered home in an official time of two hours three minutes and four seconds.
Kipchoge celebrated by raising his finger as he made the final turn but appeared to realise just before the line that he could have broken Dennis Kimetto's world record.
Kipchoge brought his hand to his forehead as he saw his time, which was just seven seconds outside Kimetto's mark made in Berlin two years ago, but was soon smiling again as he celebrated a stunning run.
Fellow Kenyan Stanley Biwott was second with a personal best of two hours three minutes and 51 seconsd, while Ethiopia's Kenenisa Bekele was third.
"I realised I ran a world record for 30, but between 30-40km I lost about 20 seconds," said Kipchoge. "I knew the record was close. I tried to squeeze it, but it wasn't possible.
"I'm happy I ran a course record. The crowd is what pushed me, it's a wonderful crowd in London. In every kilometre, except in the tunnel, they cheer you and keep you moving. The support was perfect and it was good to get a PB."
There was significant news for the homegrown contingent too, with the race doubling as the British Olympic selection trial.
Scot Callum Hawkins finished eighth in two hours 10 minutes 55 seconds to snap up the first automatic spot in Rio, with Tsegai Tewelde also booking his place in Brazil after coming in 12th.
Tewelde is from Eritrea and claimed asylum in Britain after competing in the 2008 World Cross Country Championships in Edinburgh.
Hawkins' brother Derek was third and, having also hit the Olympic standard, could be offered a discretionary place.
Kenya's Jemima Sumgong overcame a heavy fall to win her first London Marathon ahead of defending women's champion Tigist Tufa.
Sumgong took a tumble at around 23 miles, apparently tangling feet with Aselefech Mergia in an incident that also saw one of the favourites Mary Keitany fall.
Sumgong, who has been a runner-up in the Boston, Chicago and New York marathons, cracked her head against the floor but ignored her clear discomfort to rejoin the leading pack and eventually pass them.
She finished in an unofficial time of two hours 22 minutes and 58 seconds as Tufa failed to haul her in on the final stretch.
"The Ethiopian runner clipped my leg and I went down," Sumgong said of her accident. "I got up again as quickly as possible and got my pace back.
"The fall really affected me and I was unsure if I could continue. I have a cut on my head and on my shoulder, they are bleeding but I don't feel any pain yet. I did feel it in my legs, though, so I am so surprised I won."
British duo Alyson Dixon and Sonia Samuels also ensured Olympic selection after going head to head for the majority of the race.
Dixon edged it in a spring finish, but the pair celebrated as team-mates after crossing. Charlotte Purdue was the next home runner to finish on her debut over the distance and could yet join them in the summer.
David Weir was again denied a record seventh London Marathon title, as Marcel Hug won a sprint finish in the men's wheelchair race.
Weir finished second in 2014 and 2015 and was edged into third this time, with Switzerland's Hug powering towards the finish line ahead of American Kurt Fearnley.
Hug, who won the race two years ago but suffered a puncture last time around, was clocked at one hour 35 minutes and 19 seconds. Weir first won the event in 2002, adding five more titles in the next 10 years to go level with Dame Tanni Grey-Thompson with six victories.
But Hug had too much on this occasion. He led a five-man pack into the final turn and never looked like giving up his position.
Weir was in phlegmatic mood afterwards, insisting he was not fixated on a completing his magnificent seven.
"I think it's the media that hype it up so much, I don't think too much about it," he told BBC Radio Five Live. "I've been racing here since I was eight years old, doing the mini marathon, and this is my 16th year in a row I think.
"To get six victories and be in the top three a number of years is not bad going. I've got to applaud myself for that and not get beaten up about the seven.
"If it comes, it comes and if it doesn't, it doesn't. I'm happy with what I've done in my career, but I'm not saying I'm going to retire, I still feel I have more to give and I'll be back next year."
Fearnley's fellow American Tatyana McFadden continued her domination of the women's wheelchair race, claiming her fourth successive victory. She was pushed all the way by Manuela Schar but took the tape at one hour 45 minutes 20 seconds.
McFadden told the station: "Each year it's going to get tougher and tougher with athletes getting faster. It was a great day to run, the weather held up thank goodness. I was a little nervous towards the end but I found the will within and the drive within."