Rafael Espinoza stunned Robeisy Ramirez in a thrilling fight to become WBO featherweight world champion by majority decision in Florida.
A remarkable final round saw Espinoza unload a barrage of punches to score a knockdown which gave him victory with the judges scoring the bout 113-113, 114-113, 115-111 in the Mexican's favour.
Espinoza himself was floored in the fifth round by Ramirez, who is a two-time Olympic gold medallist. Had the knockdown come seconds earlier, the fight may have been over as Espinoza was saved by the bell.
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Despite clearly being shook, Espinoza dug deep and began to turn the fight around after Ramirez was deemed to slip in the sixth.
Espinoza had not fought beyond the third round for three years but was full of energy and unleashed everything in the final round.
The 29-year-old threw 995 punches to Ramirez's 376 but the latter was more consistent with the shots he landed.
There was great respect between both fighters after the verdict was delivered and an outpouring of emotion from Espinoza, who would be up for a rematch.
"I didn't think about anything in here. I just thought about winning. I even asked what round we were in. And I knew that I had to drop him in order to win. I just put my heart into it. I always do that. And thank God it happened," said Espinoza.
"I think I've had a broken foot since the second round. But what kept me on my feet was my daughter, my parents, my wife and my family. I knew that all of Mexico was watching me. And I knew that I had to become a world champion."
Ramirez added: "We did what we always do. We followed what Ismael Salas told us to do. We scored the knockdown and tried to end the fight, but it didn't happen.
"I thought the fight was won. But he got his second wind. I tried to catch mine. But I've got to give him credit. He came after me. He got the knockdown. I didn't think it would determine the result, but that's what the judges decided."
Billam-Smith vs Masternak - when are they in the ring on Sunday?
World title action takes place on Sunday evening live on Sky Sports when Chris Billam-Smith fights Mateusz Masternak.
Billam-Smith is making the first defence of the WBO cruiserweight championship he won in May when he boxes determined challenger Masternak at the Bournemouth International Centre.
The champion is having this fight on Sunday (rather than the typical Saturday fight night) to allow his hometown fans to get back from Bournemouth's away game at Manchester United the previous day
The ringwalks for the main event are expected at around 9pm on Sunday night, live on Sky Sports Arena.
The broadcast will begin at 6pm with prospect Fran Hennessy kicking off the show against Argentina opponent Lucrecia Belen Arrieta.
Olympic gold medallist Lauren Price and light-heavyweight boxer Ben Whittaker are also in action.