Ehtiopia's Tsegaye Kebede snatched victory in the final kilometre of the London Marathon in an unofficial time of two hours six minutes and four seconds.
Kebede, winner in 2010, timed his attack perfectly to overhaul tiring Kenyan Emmanuel Mutai, the 2011 champion, and pull away to win by 30 seconds.
Ethiopia's Ayele Abshero was third over the 42.195-km race. Last year's champion Wilson Kipsang of Kenya finished fifth with Ugandan Olympic champion Stephen Kiprotich sixth.
Britain's Olympic 5,000 and 10,000 metres champion Mo Farah had dropped out of the race at the halfway stage as planned.
In the women's race 28-year-old Priscah Jeptoo from Kenya clocked two hours 20 minutes 15 seconds to win comfortably ahead of her fellow countrywoman Edna Kiplagat.
World champion Kiplagat was runner up for the second successive year and Japan's Yukiko Akaba took third.
Jeptoo had been leading with Kiplagat at 30 km but began to increase her pace to leave her rival trailing and eventually won by over a minute.
Ethiopia's Olympic champion and pre-race favourite Tiki Gelana dropped off the pace after colliding with a wheelchair athlete at a drinks station at 15 km.