Filipino star Nonito Donaire knocked out Mexico's Jorge Arce at the end of the third round, for his 30th win in a row, to keep the World Boxing Organization super bantamweight crown.
Donaire on Saturday landed a powerful left hook to Arce's chin that sent Arce to the canvas and referee Laurence Cole stopped the fight at 2:59 of the third round.
"I went out and pretty much timed him," Donaire said. "We wanted to slow him down and get him thinking he could get in there. We knew he would open up.
"I've never really gone and hit with the left hook, but I knew I was going to go out there and give it everything, no matter what."
Donaire improved to 31-1 with his 20th career knockout. He has not lost since the second fight of his career back in 2001.
The victory brought some joy for Filipino fight fans still stunned at Manny Pacquiao's knockout loss a week ago to Mexico's Juan Manuel Marquez.
"There were a lot of fans who were like, 'You have got to get him. This is for the Philippines.' I hope they can be proud of what I did," Donaire said.
Arce, 33, fell to 61-7 with two drawn bouts, in what he said was the final fight of his career.
"My career is over. I'm leaving after losing to the best man," Arce said. "He is very good. He has power. He can finish the fight at any moment.
"I promised my family if I lost I would leave. I retire to go home and watch the fights on TV."
Donaire scored a knockdown of Arce with a powerful straight right hand about a minute into the second round, forcing the challenger to touch his gloves and a knee to the canvas.
Donaire, 30, again knocked Arce to the canvas with a pair of left hooks late in the second round and, in the third, landed the knockout blow to end it.
"I got him with a straight right and the counter hook came in after that," Donaire said.
Donaire had beaten South African Jeffrey Mathebula last July and Japan's Toshiaki Nishioka in October in prior title defenses after taking the vacant crown with a split decision last February over Puerto Rico's Wilfredo Vazquez.
Arce had nine wins and a draw since last being beaten, by South African Simphiwe Nongqayi in 2009.