Deena Kastor put in a dominant display to win the women's London Marathon.
Kastor won Olympic bronze at the Athens Games in 2004
The 33-year-old American, the pre-event favourite, appeared to damage a wrist when she stumbled into one of the food tables as she tried to grab a drink.
The incident failed to knock her out of her stride, though, as she became only the eighth woman to clock under two hours and 20 minutes for the distance.
Kastor won in 2hrs 19mins 35secs, finishing ahead of Russia's Lyudmila Petrova and Kenyan Susan Chepkemei.
"I did want to run faster but I wasn't feeling it early on," said Kastor, who added that training had gone well. "I managed to hold on to go under 2:20 which was my main goal."
Kastor dominated the race as she shattered the American record of 2hrs 21mins 16 secs she set three years ago in London when she finished third behind Paula Radcliffe.
The world record-holder did not defend her title because of a foot injury.
Britain's Mara Yamauchi ran a personal best to come home sixth in 2:25:13 - a time which puts her second behind Radcliffe on the British all-time list.
She said: "I was struggling at 17 miles because I was out on my own. I had to keep it together till the end.
"The crowd support was good despite the weather and the conditions were perfect for a fast time. I'm pleased that I ran a personal best."
Kastor's confident front-running display saw her shake off Chepkemei before the 17-mile mark.
The Olympic bronze medallist, paced to 23 miles by male training partner Mike McKeeman and then Kenyan Henry Tarus, never looked back after the decisive break.
Her only other marathon victory was in Chicago last year and she becomes the first American to win the London race.
Women's London Marathon:
1. Deena Kastor (United States) 2 hours 19 minutes 36 seconds
2. Lyudmila Petrova (Russia) 2:21:29
3. Susan Chepkemei (Kenya) 2:21:46
4. Berhane Adere (Ethiopia) 2:21:52
5. Galina Bogomolova (Russia) 2:21:58
6. Mara Yamauchi (Britain) 2:25:13
7. Constantina Dita (Romania) 2:27:51
8. Salina Kosgei (Kenya) 2:28:40
9. Margaret Okayo (Kenya) 2:29:16
10. Eri Hayakawa (Japan) 2:31:41