RIO DE JANEIRO — Mohamed Farah of Britain became the first man in 40 years to win gold medals in the 5,000 and 10,000-meter races in two separate Olympic Games.
He won the 5,000 on Saturday night with his trademark fast finish. Paul Chelimo of the United States won the silver and Hagos Gebrhiwet of Ethiopia the bronze.
Last early on, Farah slowly moved his way up the field, finally joining the leaders with five laps to go. The field was still tightly bunched at the bell when he unleashed his devastating kick to win going away.
Lasse Viren of Finland was the last man to win those double-golds at two Olympics, completing the feat at the 1972 and 1976 Games.
Running in the 10,000 a week ago, Farah stumbled toward the track after getting tangled with Galen Rupp of the United States, his friend and training partner, in the 10th lap of the race. Nevertheless, he finished in 27 minutes 5.17 seconds to win the third gold medal of his career.
On Wednesday, in his 5,000-meter heat, Farah tripped again when he collided with Hassan Mead of the United States with about 150 meters left to go in the race. Farah regained his balance and finished in second to safely qualify for the final.
But Muktar Edris, Dejen Gebremeskel and Gebrhiwet, all of Ethiopia, were on hand to threaten Farah’s chances.
Farah, 33, has been invincible in the last five years. He lost only one 5,000-meter race since 2011, when he moved to Oregon to work with coach Alberto Salazar: the 2013 Prefontaine Classic in Eugene, Ore., which he ran while battling a stomach virus.
It has been reasonable to wonder, given Farah’s age, if his invincible form might begin to show some decline. It has not yet.