Floyd Mayweather Jr. had his nose bloodied midway through the fight, but maintained his poise to remain undefeated and claim the WBA junior middleweight title from Miguel Cotto.
Mayweather won by unanimous decision on Saturday night.
The 35-year-old (43-0, 26 KOs) was tested early and often by Cotto (37-3, 32 KOs), but the five-division champion started to pull away in the later rounds.
Two judges scored the fight 117-111 and the third judge gave it 118-110.
After the judges' decision, sold-out crowds booed Mayweather at the MGM Grand in Las Vegas.
"When it's pay-per-view and the fans are paying and the fans are coming out to see you, you want to give the fans excitement," Mayweather said.
Cotto, 31, gave Mayweather all he could handle, tagging his competitor with shots to the head most of the night. But Mayweather was more accurate with his punches.
In the end, Cotto earned the respect of his opponent.
"You're a hell of a champion," Mayweather said. "You're the toughest guy I ever fought."
After the fight, Mayweather was asked about the likelihood of facing Manny Pacquiao -- something boxing fans have wanted for years.
"If you're the best, take the test," Mayweather said, referring to his insistence that Pacquaio submit to Olympic-style drug testing and has served as a stumbling block to making the fight happen. Pacquiao has said he would agree to such testing.
Regardless, Mayweather's next fight will have to wait. On June 1, he starts a three-month jail sentence for misdemeanor domestic violence and harassment charges involving a former girlfriend.
Mayweather will make a guaranteed $32 million, which is a state record, according to the Nevada Athletic Commission. Cotto will make $8 million -- the largest purse of his career.