Los Angeles - Deontay Wilder dropped Eric Molina three times before knocking him out in the ninth round on Saturday to retain his World Boxing Council heavyweight world title before delighted home fans in Birmingham, Alabama.
Wilder was making his first defence of the title he won in January, when he became the first American since Shannon Briggs in 2007 to claim a piece of the heavyweight world title.
The 29-year-old American improved to 34-0 with 33 wins inside the distance.
His unanimous decision over Bermane Stiverne for the title on January 17 marked the only time he's been taken a full 12 rounds, and on Saturday he lived up to his pledge to get back to the business of knockouts.
A straight right from Wilder spun Molina around, with the following blows sending him sprawling and prompting referee Jack Reiss to signal that the fight was over at 1:03 of the round.
The Texan, who rattled the champ with a left hook in the third round, was knocked down by a left hook late in the fourth that sent him sprawling into the ropes.
He survived the count from Reiss and was lucky it came so close to the bell.
But Wilder sent him down again early in the fifth with a right to the head, and later in the round with a barrage that included a punishing right uppercut and a right to the body.
"You've got to protect yourself," Reiss admonished Molina before he let the fight continue.
And in the sixth, Molina seemed to have found a second wind, pressing forward despite absorbing another hard left hook.
He was hurt again in the seventh, but got in some effective work to Wilder's body in the seventh and eighth before the champion found the punch to end it.
"We made history tonight," Wilder said in a shout-out to his home-state fans.
The card at the Bartow Arena on the University of Alabama at Birmingham campus featured the first world title fights in Wilder's home state -- where past champions Joe Louis and Evander Holyfield were born.
Wilder admitted he was surprised Molina, who fell to 23-3 with 17 knockouts, took him so deep into the fight.
"This guy's got heart," he said. "I needed a tough guy. I needed a guy that had heart. I needed a guy that was going to get dropped and come back up.
"I respect him," added Wilder, who is aiming to supply a needed shakeup to the heavyweight division in which Ukrainian Wladimir Klitschko - unbeaten since 2004 - holds the World Boxing Association and International Boxing Federation belts.
On the undercard, Puerto Rico's Jose Pedraza claimed the vacant International Boxing Federation super-featherweight world title with a lopsided unanimous 12-round decision over Russian Andrey Klimov.
Pedraza, nicknamed "Sniper," dominated throughout, with two ring-side judges giving him the decision 120-108 and one seeing it 119-109.
Pedraza improved to 20-0 with 12 knockouts.
From the first round, Klimov could find no answer for Pedraza's hand speed and combinations.
By the end of the eighth round the Puerto Rican had Klimov bloodied, with swelling under his left eye, but coasted home for the decision.
Klimov fell to 19-2 with nine wins inside the distance.