Deontay Wilder recovered from a seventh-round scare to retain his World Boxing Council heavyweight title on Saturday and keep intact his record of knocking out every opponent he has faced.
Wilder knocked down Cuba's Luis Ortiz three times in the fight, finishing off the previously unbeaten challenger with a right uppercut as the referee stopped the fight with 55 seconds left in the 10th round.
The 32-year-old Wilder improved to 40-0 with 39 knockouts as he made the seventh defence of his heavyweight title.
Wilder knocked Ortiz down in the fifth and twice in the final round but Ortiz made him work for the victory at Barclays Center arena in New York. Wilder barely survived the seventh after Ortiz surprised him with a right hook and left hand combination and followed it up with a barrage of his own.
This was the first career title fight and first loss for the stout Ortiz who weighed in at 241 pounds, almost 30 pounds heavier than the taller and leaner 6-foot-7 Wilder.
Wilder has been trying unsuccessfully to get a unification fight with two-belt titleholder Anthony Joshua and now hopes this win is a stepping stone to more heavyweight hardware.
But with no date set to fight England's Joshua, Wilder had to face the dangerous counter-punching Ortiz (28-1).
Wilder hopes to next fight the winner of a Joshua-Joseph Parker unification title fight on March 31 in Cardiff, Wales.
"I am ready right now. I want to unify. I am ready whenever those guys are," Wilder said.
Wilder gives Parker a shot at the upset - and warned Joshua that a boxer with a lot of "heart" could overcome an opponent with a weight advantage and big muscles.
"I think Parker has a 100 percent chance of winning that fight, he just has to be smart and stick with the game plan," added Wilder.
"In this ring it's not about how much a person weighs, it's not about how big a person's muscles are, it's all about their heart."