Leon Edwards delivered the head kick heard "round the world" on Saturday night.
Edwards knocked out Kamaru Usman in the fifth round on a left kick to the head to claim the welterweight title at UFC 278 in Salt Lake City.
Usman had controlled the entire fight and was beating Edwards handily until the challenger connected at the 4:04 mark of the fifth and final round. Usman led 39-37 on all three judges' cards.
"I can't put it into words," Edwards said.
Edwards snapped Usman's 15-fight winning streak, one shy of Anderson Silva's UFC record.
The fight was a rematch of a December 2015 bout, won by Usman via unanimous decision. Edwards has not lost since that fight.
Edwards improved to 12-2 (1 NC) in UFC.
Usman had five successful title defences since defeating Tyron Woodley for the welterweight belt in March 2019.
Al Ain crushed 10-man Yokohama F Marinos 5-1 in the second leg of the Asian Champions League final on Saturday to register a 6-3 aggregate win and their first continental title in 21 years.
Fourteen-time French Open champion Rafa Nadal said there was still a chance this year's tournament in Paris may not be his last in comments ahead of his tough opener against fourth seed Alexander Zverev.
Outgoing Barcelona manager Xavi Hernandez said he was proud of his achievements with the club and was looking forward to being a fan again as he prepares to coach his final game against Sevilla.
World number one Novak Djokovic does not consider himself a favourite ahead of his title defence at the French Open, which begins with a first-round match against local hope Pierre-Hugues Herbert on Sunday.