CARSON, Calif. - Andre Berto spent five years regretting his inability to land the punches that would have finished off Victor Ortiz during his first career defeat.

With a second shot at his rival, Berto didn't miss.

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Berto stopped Ortiz with two knockdowns in the fourth round Saturday night, avenging his loss in the welterweight stars' first bout five years ago.

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Berto (31-4, 24 KOs) rebounded ferociously after Ortiz knocked him down in the second round of their rematch. Berto floored Ortiz the first time with a right uppercut, and Ortiz went down again moments later from a series of big punches.

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Ortiz crawled back to his feet and barely beat the count, but didn't respond when asked if he wanted to continue. Referee Jack Reiss stopped the bout 1:14 into the fourth.

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Berto returned to the ring in style after his one-sided loss to Floyd Mayweather Jr. last year in the pound-for-pound champion's final fight. Berto lost his WBC welterweight title and his unbeaten record to Ortiz in their 2011 bout, and he went 3-3 in his six fights since.

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Ortiz and Berto knocked each other down twice in their wild first fight in 2011, each flooring the other in the sixth round alone. Ortiz hung on for a decision despite losing a point for hitting behind the head in one of the most entertaining high-level fights of this decade.

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The loss was the fourth in six fights for Ortiz (31-6-2), who has struggled with injuries and inconsistent performances ever since his title-winning victory over Berto. After getting booed in the ring, Ortiz was grabbed by a fan on his way to the dressing room, setting off a brief fracas in the crowd of 7,760 at StubHub Center's famed outdoor ring south of downtown Los Angeles.

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Still, Ortiz was booed by fans who have a tumultuous relationship with the former champion fighting out of Ventura, California. Ortiz has been criticized throughout his career for the endings to his fights, particularly losses to Marcos Maidana and Josesito Lopez in which fans hoped he would continue.

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Berto might have earned a shot later this year at Danny Garcia, the WBC welterweight champion who watched from ringside. Both fighters are represented by Premier Boxing Champions.

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