Floyd Mayweather (43-0, 26KOs) has called Miguel Cotto (37-3, 30KOs) the toughest opponent he has fought.

"You're a hell of a champion," Mayweather told Cotto afterward their WBA light-middleweight title bout in Las Vegas on Saturday night. "You're the toughest guy I ever fought."

"He's a tough competitor," Mayweather said later. "He came to fight; he didn't just come to survive. I dug down and fought him back."

Mayweather, who is nicknamed "Money" and was guaranteed $32 million for the fight, was forced to fight every minute of all 12 rounds against the Puerto Rican champion. He did it after weighing in at 151-pounds, the heaviest he has ever been for a fight.

The weight didn't seem to affect Mayweather, and neither did the heavier 10-ounce gloves at super-welterweight. But he took some punishment before coming back to dish some out in the later rounds.

"When you fight on pay-per-view you have to give the fans what they want, and that's excitement," Mayweather said.

Cotto was guaranteed his biggest purse ever, $8 million.

Mayweather used used his speed and accuracy to win a unanimous decision. He rocked Cotto in the final round to remain unbeaten in 43 fights.

But it wasn't easy, with Cotto fighting until the final bell.

THREE MONTHS IN JAIL

Fighting just a few weeks before he enters a county jail to serve a three-month sentence for domestic abuse, Mayweather found himself in a tough fight against a game opponent who never stopped moving forward.

In the last round, Mayweather landed his best punch of the night, a left uppercut that seemed to hurt Cotto. He followed that with several flurries to the head to wrap up the decision that was roundly booed by some spectators.

Cotto came out looking slow and overmatched in the first round, but quickly settled into a routine, attacking Mayweather from behind his left jab.

Mayweather got more aggressive coming out to start the fourth round, and landed a series of rights to the head that stunned Cotto and kept him from moving forward effectively.

Mayweather fought good portions of the fight on the ropes, using them for leverage and counterpunching to Cotto's head when he opened up.

"He's ready to quit," trainer Roger Mayweather told his nephew after the sixth round.

But Cotto was relentless, coming forward and hitting Mayweather with good shots to the head.

Toward the end of the eighth round he landed several punches to the head, prompting Mayweather to shake his head as if they didn't hurt, but by then Mayweather was bleeding from the nose and looked like he had taken some punishment.

Punch statistics showed Mayweather landing 179 of 687 punches to 105 of 506 to Cotto.