Eliud Kipchoge broke the course record at the Virgin London Marathon, retaining his title with the second-fastest run in history over the distance.
The 31-year-old Kenyan 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 2.03:51, while Ethiopia's Kenenisa Bekele was third.
Kenyan runner Eliud Kipchoge has won the men's London Marathon with a course record time of 2:03:06.
British astronaut Tim Peake is running a marathon on a treadmill in space so he can "join" runners in the London Marathon.
Kenyan runner Jemima Sumgong has crossed the finish line of the women's London Marathon with a winning time of 2:22:58.
Despite suffering a heavy fall near the end of the race, the 31-year-old picked herself back up and went on to beat last year's winner, Ethiopian Tigist Tufa, in a close final mile.
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.
Women runners hit 25 mile mark in the London Marathon, says ITV News reporter Sejal Karia.
#LondonMarathon Women at 25 mile mark. Exciting too in Men's race, at 19 miles also between 2 contenders. Kipchoge & Biwott both from Kenya
The London Marathon clear-up operation will remove over seven tonnes of rubbish, four tonnes of recycling and 40,000 plastic water bottles.Read the full story ›
Astronaut Tim Peake's partner runner on earth Tyrone has kicked off on the London Marathon.
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Astronaut Tim Peake has tweeted his London Marathon shadow runner Tyrone from space.
There are 70 years between the oldest and youngest runners at this year's London Marathon.
Race veteran Iva Barr, 88, from Bedford, said the day feels "like being at the centre of a big street party". She will run her 20th London Marathon, raising money for disabled young people's charity Whizz-Kidz.
Rebecca Manners from Manningtree in Essex will celebrate her 18th birthday by running the route alongside her parents, in aid of VICTA, which supports blind and visually impaired children.
This year's runners face a chilly start and spectators are being urged to wrap up warm with a high of just 12C (54F) forecast for the day.
British astronaut Tim Peake has posted a picture of London from space as he prepares to join marathon runners today from a treadmill in space.
He posted a picture gearing up thousands of runners ready to take on the challenge today.
Peake will be pounding alongside them in a virtual marathon competed on a treadmill in the International Space Station.