Kelvin Kiptum shattered the men's marathon world record, finishing in 2:00:35 in Chicago.
He beat Eliud Kipchoge's previous mark by over 30 seconds.
What happened?
Kiptum won the Chicago Marathon, breaking the tape 3 minutes and 27 seconds ahead of Benson Kipruto.
He wore the new Nike supershoe, approved by World Athletics as the Nike Dev 163.
The race details
Kiptum and Daniel Mateiko broke away from the pack by the 10-kilometre mark.
They were over one-and-a-half minutes ahead of the field by the halfway point.
The new supershoe
The Nike Dev 163 is seen as a response to Adidas' Adizero Adios Pro Evo 1.
This shoe was used by Tigist Asseefa to break the women's marathon world record last month.
Kiptum made it a one-man race at 35 kilometres, taking advantage of Chicago's flat course.
He shifted into another gear, deciding to try for a sub-2:00 finish.
Reaction to the record
Former AFL champion Kane Cornes tweeted about Kiptum's incredible performance.
Journalist Chris Chavez said Kiptum's record was a sign that a sub-2:00 marathon was imminent.
Kiptum glided through the finish line, seemingly with energy to spare.
He leapt into an embrace with race director Carey Pinkowski.
The women's race saw a remarkable effort from Dutch middle-distance runner Sifan Hassan.
She thwarted Kenya's Ruth Chepngetich's bid for a third straight Chicago title, finishing in 2:13:44.
Kiptum's record-breaking run has sparked excitement about the future of marathon running.
The 23-year-old's performance has shown what is possible with the new supershoe technology.