The uncertainty that lingered over Srisaket Sor Rungvisai's first victory over boxing's former pound-for-pound king Roman "Chocolatito" Gonzalez fueled the Thai fighter's preparation for Saturday's rematch.
"I trained four months because I wanted to knock him out," Sor Rungvisai said.
In the fourth round, Sor Rungvisai followed a knockdown of Gonzalez earlier in the round with a more crushing right hand that put Gonzalez flat on his back with his eyes closed for several seconds.
"I wanted every Thai person to know what I came here for," Sor Rungvisai (44-4-1, 40 knockouts) said after defending his World Boxing Council super-flyweight title, a stunning close to a compelling night of three super-flyweight battles before a sold-out crowd of 7,418 at StubHub Center.
Mexico's Juan Francisco Estrada won a mandatory title shot at Sor Rungvisai by knocking down countryman Carlos Cuadras in the 10th round to claim a unanimous victory by scores of 114-113, and World Boxing Organization champion Naoya Inoue improved to 14-0 when challenger Antonio Nieves' corner threw in the towel after six rounds.
But the night's star was Sor Rungvisai, who repeatedly pressed the action on Gonzalez (46-2) after edging him in a disputed majority decision victory March 18 at Madison Square Garden.
In that bout, Gonzalez shrugged off a first-round knockdown and landed more punches on Sor Rungvisai.
Saturday night was believed to be about Gonzalez's redemption, as numerous supporters helped fill the venue.
"You saw Roman pack the house. Srisaket came into hostile ground and showed he's a true champion," promoter Tom Loeffler said.
The knockout came 1 minute, 18 seconds into the fourth as Sor Rungvisai smashed Gonzalez in the head with a power right hand that left Gonzalez on his back for minutes before he could raise his head and open his eyes as Sor Rungvisai celebrated.
Gonzalez was transported to a local hospital for precautionary reasons.
"We were both trading punches. His were landing harder," Gonzalez said. "I was very hurt the second time I was knocked out, but I think I'll be OK."
Loeffler said he can stage a Sor Rungvisai-Estrada bout by early 2018, and that by winning "convincingly," Sor Rungvisai has emerged as "one of the best fighters in the sport."
"I'm not afraid of anyone. I'll fight whoever," Sor Rungvisai said.
Estrada not only had to endure the crazed punching of Cuadras, but he also had to weather a slip when the winner was announced.
Hall of fame ring announcer Michael Buffer first said all three judges had scored the super-flyweight bout in Cuadras' favor, before correcting himself and announcing that Estrada had won.
"I felt like I was being robbed," said Estrada (36-2), a former flyweight champion who roared back to score a narrow victory over the former super-flyweight champion Cuadras.
Meanwhile, in his U.S. debut, Japan's Inoue eliminated such intrigue, battering Nieves with vicious body shots.
Nieves was knocked down in the fifth by a rattling left that struck the challenger directly on the belly button, and after another round of abuse, Nieves' corner stopped the fight as Inoue improved to 14-0 with 12 knockouts.
"He's a brave warrior, but I was too good for him," said Inoue, whose victory sets up a series of interesting showdowns in the packed division. "I will fight anybody."
Nieves, outlanded in punches 118-45, endorsed the champion: "He's very strong, very quick. He keeps throwing the same combinations and they never stop. He's relentless."