Saul ‘Canelo’ Alvarez beat Turkish challenger Avni Yildirim to defend his WBC and WBA super-middleweight titles in Florida.
Yildirim retired before the start of the fourth round after being knocked down by the Mexican in the third.
Alvarez, 30, is a four-division world champion who now boasts a record of 55 wins, one draw and two defeats, including 37 knockouts.
“I wanted to have a great fight and I did what I had to do,” said Alvarez.
“I needed a knockout and that’s what I did. It doesn’t matter if they’re taller, if they’ve got more reach, or they’ve got a good trainer.
“I came to do my job, I came here to win.”
Fighting in his first bout since beating Britain’s Callum Smith in December, Alvarez dominated the early exchanges at Miami’s Hard Rock Stadium and floored his opponent with a crisp left-right combination.
After the fight, promoter Eddie Hearn said the Mexican wanted to fight Britain’s world champion Billy Joe Saunders to add the WBO belt to his collection on 8 May.
The Saunders fight will be the next step in Alvarez’s bid to become the first undisputed super-middleweight champion in boxing history.
“No-one has done it,” Alvarez said. “I want to make history. No-one has done it at 168 [pounds].”