World record holder Wilson Kipsang and twice world champion Edna Kiplagat led Kenyan domination at the London marathon on Sunday as Britain's Mo Farah toiled on his highly-anticipated debut.
Farah, the world and Olympic 5,000 and 10,000 metres champion, came home eighth as Kipsang secured a second London title with a course record two hours four minutes 29 seconds.
He kicked clear of compatriot Stanley Biwott who was 26 seconds back with Ethiopian Tsegaye Kebede third.
Farah, who was never in contention after dropping behind the leaders from the start, gritted his teeth to cross in 2:08:21, outside the British record.
"I will be back," Farah told the BBC. "I'm not going to finish it like this. I gave it my all but I'm disappointed I didn't go out there and give what the crowd deserve.
"It was pretty tough. I'm quite disappointed but you try things and if they don't work, at least you gave it a go. I missed one drink station but it was really just the pace - I should have gone with the front group. The pacemakers were slightly ahead of me but you learn - life goes on."
Edna Kiplagat won her first London title after finishing runner-up in the past two years, getting the better of compatriot Florence Kiplagat in the final 200 metres to win in two hours, 20 minutes and 21 seconds.
Kiplagat outkicked her namesake who finished three seconds behind with Ethiopian Tirunesh Dibaba, making her marathon debut after a glittering track career, taking third, 14 seconds behind the winner.
Last year's London winner Priscah Jeptoo dropped out of the race at around the 25-km mark while Olympic champion Tiki Gelana finished ninth.
Kiplagat, the two-time reigning world champion, made up for the pain of finishing runner-up for the past two years in London to take the title, with her namesake three seconds back.
Tirunesh Dibaba, the Ethiopian track great stepping up to 26.2 miles for the first time, had looked set to challenge the pair for much of the race, but paid the price for dropping a water bottle and having to stop to pick it up. She finished in third, 14 seconds adrift.
Ireland's Nicola Duncan (Galway City Harriers) ran a personal best of 2:33:28. The time was inside the qualifying standard (2:38) for the European Championships in Zurich in August