True to his word, Margarito pressured Cotto throughout their scheduled 12-round slugfest, and he knocked down Cotto twice in a 30-second span in the 11th round. Referee Kenny Bayless, seeing that Cotto had taken enough punishment, as did Cotto's corner, stopped the fight with 55 seconds remaining in the round.

It was the first time Cotto had tasted defeat in his professional career as he fell to 32-1. Margarito improved to 37-5 with 27 knockouts.

"Obviously, Cotto is a very strong fighter," Margarito said. "I told my corner I could wear him down and knock him out, and that's what I did.

"He's a great fighter and a great champion, but I had to put pressure on him, and eventually I broke him down."

Both fighters took a beating, though Cotto paid a heavier price. He had numerous welts around his eyes and might have a broken nose. He was taken to Valley Hospital for observation.

"I am very proud and very happy that I was able to give the fans a great fight," Cotto said before leaving for the hospital. "This night was Margarito's night. He's an excellent fighter, and he did his job better than I did."

The two fighters combined to connect on 547 punches, including 406 power punches -- 237 of them landed by Margarito.

Cotto, who earned $3 million for the fight, was a minus-220 favorite as he was looking to make his fifth consecutive successful title defense.

But Margarito, who took all the late betting action and closed at plus-190, was not fazed. As promised, Margarito was moving forward, looking to stay on top of Cotto.

Cotto, ever the master boxer, negated the attack and countered brilliantly, using his left jab to tag Margarito. But Margarito showed a strong chin and returned fire, bloodying Cotto's nose in the second round and nailing him with a right to the body as he was trying to turn it into a street brawl.

However, Cotto never flinched. He kept using the left jab effectively, landing it often and with deadly accuracy.

His defense might have been even better than his offense. Cotto dodged most of Margarito's bombs, and even when the Mexican connected, Cotto shrugged it off and went back to work.

Cotto was ahead on all three judges' scorecards when the sixth round began. But Margarito wasn't going away. In fact, he was just getting warmed up.

He got the best of Cotto in the sixth and then hurt him in the seventh with a body-head combination that had Cotto holding on.

"He never hurt me," Margarito said. "But that was the game plan. Once the sixth round came, it was time for me to press the action. I started slow but came on once the sixth round started. I could feel him getting weaker, and I knew it was my time."

Margarito was building momentum and kept pursuing Cotto. He nailed him a couple of times late in the eighth round and, with most of the announced crowd of 10,477 behind him, tried to gain complete control of the fight.

By the 10th round, Cotto's offense had crawled to a halt, and his once-impenetrable defense was being exposed as Margarito cracked him to the body and the head.

By the 11th, Margarito was completely in control. He took a combination to the face early, only to answer with a flurry to Cotto's head, which led to the first knockdown. Three chopping right hands by Margarito sent Cotto to the blue canvas.

Cotto was a hurt fighter at this point, and Bayless wisely stopped the bout shortly after Cotto hit the deck a second time following a barrage to the body and head from Margarito.

When the fight was stopped, Margarito was ahead with judges Glen Hamada and Jerry Roth, both who scored it 96-94, and Dave Moretti had it even at 95-95.

"I trusted my preparation," said Margarito, who earned $1.5 million for Saturday's performance, and, more important, set himself up for bigger paydays down the road as the WBA welterweight champ. "Slowly, the tornado rumbled, and I told my corner that the knockout would come, and the knockout came."

Cotto, who was surrounded by a shocked group of family and close friends in his dressing room, said he'll take time off and figure out his future.

"Life continues," he said. "It's not over for me. I'm going to take a long rest and decide what to do next."

The main undercard bout saw Cesar Canchila recover from a second-round knockdown to dominate Giovani Segur and win the WBA interim light flyweight title. Canchila earned a 12-round unanimous decision with scores of 117-110, 115-112 and 117-110.

Contact reporter Steve Carp at scarp@ reviewjournal.com or 702-387-2913.