Australian southpaw Vic Darchinyan was stopped by Nonito Donaire in the ninth round of their non-title bout in Texas on Saturday to boost the Filipino star's bid to return to boxing's elite.
Donaire was trailing on two of three judges' scorecards when he snatched the victory in the second-last round in a rematch of the former world champions trying to revive their careers.
He felled Darchinyan with a left hook, and although the 37-year-old rose and continued, he never looked steady.
Donaire's punishing follow-up prompted referee Laurence Cole to call a halt at 2:06 of round nine.
Darchinyan, the fight was a grudge match after his 2007 fifth-round knockout loss to Donaire that was the Armenian-born and raised boxer's first career defeat.
The loss drops Darchinyan's record to 39-6-1.
Donaire improved to 32-2 with 21 knockouts. He bounced back from a loss to Cuban Guillermo Rigondeaux in a super bantamweight world title bout in April.
Even in the glow of victory, Donaire said his thoughts were with people in his native Philippines, where more than 10,000 are feared dead in the wake of Super Typhoon Haiyan.
"First and foremost, prayers to people in the Philippines who were hit by the typhoon," he said. "Please have your prayers for people in the Philippines."
Both fighters hurt each other with heavy blows in the second round.
A furious exchange at the end of the fourth had to be broken up after the bell, and the toe-to-toe action continued in the fifth with Darchinyan seeming to have the edge.
Donaire, who had right shoulder surgery after losing to Rigondeaux, looked tentative at times. He admitted there was a moment when he wasn't sure he could continue.
"When he hit me in my cheek, I felt like he broke my cheek," Donaire said. "Part of my mind was like, 'Is this it for me? I'm losing the fight. Should I keep going?'
"I put my heart into it," he said. "I said, 'You know what, I will never, ever quit.'"
On the same card, unbeaten American Mikey Garcia survived a second-round knockdown to knock out Roman "Rocky" Martinez with a left hook to the body in the eighth round and take the Puerto Rican's WBO super featherweight world title.
Garcia improved to 33-0 with 28 wins inside the distance. Martinez fell to 27-2-2 with 16 knockouts.