Kelvin Kiptum of Kenya won the Chicago Marathon on Sunday with a world-record time of two hours, 35 seconds.
Kiptum shattered the previous men's marathon record held by Eliud Kipchoge of Kenya by 34 seconds.
Kipchoge set that mark last year at the Berlin Marathon.
Kiptum, 23, has burst onto the marathoning scene by running three marathons in the past 10 months and posting three of the six fastest times in history.
He finished in 2:01:53 last December in Valencia, Spain, and got the time down to 2:01:25 in April's London Marathon.
"A world record was not in my mind today," Kiptum said on the NBC Chicago broadcast. "But I knew one day, one time I will be a world-record holder."
Sifan Hassan of the Netherlands posted the second-fastest women's marathon time in history, winning the women's race in Chicago in two hours, 13 minutes and 44 seconds.
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