Sammy Wanjiru won Kenya's first ever gold in the men's marathon, breaking the Olympic record despite the soaring heat in Beijing.
Wanjiru, who was among the leading pack which set the fast early pace, pulled away in the final kilometres to win in 2 hours six minutes and 32 seconds.
Morocco's Jaouad Gharib won silver, trailing by 84 seconds, while Ethiopian Tsegay Kebede took bronze.
Dan Robinson, Britain's only representative, finished in 24th spot.
The Briton was in 74th place after the first five km, which was run in a blistering 14mins 52secs in hot and humid conditions.
"They went off so quickly in the first kilometre I deliberately backed off the pace," said the 33-year-old who finished in a time of 2:16.14.
606: DEBATE
"I'm a little disappointed not to make the top 20, but you can only do what you can. Maybe I didn't get my pacing quite right, but I'm satisfied with the run."
Wanjiru, 21, and compatriot Martin Lel set a punishing pace in the first five km which reduced the leading pack to eight, with Spain's Cheme Martinez the only non-African.
The leading pack was then whittled down to five as Wanjiru upped the pace a notch at the 15km mark, and 20km later only Wanjiru, Gharib and Ethiopia's Deriba Merga could sustain the phenomenal tempo.
Wanjiru, who was running in his third marathon, always looked the stronger of the trio and the Kenyan broke clear to win comfortably, breaking the 24-year-old Olympic record set by Carlos Lopes.
His margin of victory was such that Wanjiru had time to raise his left arm aloft and clap to the crowd in the Bird's Nest stadium several times during his final lap.
Two-time world champion Gharib and Merga were left to fight it out for silver and bronze, but the latter fell away in the last two km to finish fourth.
Wanjiru, runner-up in the London Marathon in April, said: "I had to push the pace to tire the other runners. I had to push the pace because my body gets tired when I slow down.
"In Kenya we have many medals, but I'm glad to have this one. It feels good to make history for Kenya and win the gold."
Several of the favourites, including defending champion Stefano Baldini of Italy, failed to cope with the hot conditions.
The 37-year-old was out of contention early on and had settled for a 12th-placed finish.
"It was incredible what the Africans managed to do in those last 10km," said the European champion.
"This was my last marathon and my last international event. I want to carry on running, but without the stress."
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