Britain's Mo Farah overcame the shock of a mid-race fall to take a second straight Olympic 10,000m title and extend his remarkable record at global championships.
The 33-year-old produced a trademark surge over the last 100 metres to time 27min 05.17sec in the 25-lap race.
Kenyan Paul Tanui won silver in 27:05.64 with Ethiopian Tamirat Tola third in 27:06.26.
Farah tumbled in the 10th lap after being clipped by American training partner Galen Rupp.
But he brilliantly recovered to accumulate a second 10,000m title to add to the 5,000m gold he also won in London four years ago.
"When I went down, I thought, 'Oh my God, that is it.' I just got up and wanted to stick with the guys and stay strong," Farah said.
"It's never easy but everyone knows what I can do."
Farah added: "I thought about all my hard work and that it could all be gone in a minute.
"I wasn't going to let it go. I got up quickly. I thought about my family. It made me emotional."
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Rupp, the silver medallist in London who will also compete in the marathon in Rio, blamed the fall on pushing.
"I bumped into him. There was a lot of pushing. Guys slowing down in front, guys pushing from behind," said Rupp, who trains with Farah under Oregon-based Alberto Salazar.
It was his eighth successive win in the 5,000 or 10,000m at a world championships or Olympics since 2011, when Ibrahim Jeilan beat him over 10,000m in the Daegu world championships.
Farah has also notched up the European double, twice, in 2010 and 2014 to become one of the best middle distance runners of all time.
The 34 runners at the Olympic Stadium went through the first five laps at a steady pace, Farah working his way to the front after at first coasting at the back of the pack.
Ethiopian pair Tola and Yigrem Demelash, the fastest man over the distance this season, immediately responded, Farah falling in with Rupp and exchanging a few words.
But there was drama to come, Farah taking a tumble during the 10th lap after being clipped by Rupp.
The Briton recovered quickly and flashed the American a thumbs-up as he refound his rhythm behind Tola, Tanui and his teammate Geoffrey Kamworor, the reigning world cross country champion and the winner of the IAAF World Half Marathon Championships earlier this year.
"Obviously I didn't want that to affect the outcome of
the race at all," said Rupp.
"I wanted to make sure he was okay first and foremost. I told him to get behind me after that and tried to lead him back up. I'm just happy that it didn't affect the outcome for his race."
Rupp added: "Mo never loses his head, he's always able to keep his composure. He's just a great competitor."
At the halfway mark, the field began to break up, the Kenyan duo taking up the front running. Team tactics then showed through, the third Kenyan, Bedan Karoki Muchiri, accelerating to the front.
His compatriots swept along with him, Farah looking comfortable in fourth as the pack slowed after the latest surge.
Demelash moved past Farah with six laps to run, another increase in the pace of the leading pack proving tough for anyone out of the top 10.
Farah, a regular competitor over 1500m to improve his speed work, led with two laps to run, holding off Tanui on his shoulder, Rupp behind him.
The Briton was passed by Tanui after going through the bell, but Farah held his nerve as a grimacing Tanui faded to time 55.37sec for the final lap.