LAS VEGAS >> For 11 rounds, Sergio Martinez did everything he wanted, including giving Julio Cesar Chavez Jr. the beating he promised.

Then came a wild 12th round that will be talked about in boxing for a long time to come.

Bleeding from the nose and his face bruised from the hands of Martinez, Chavez somehow found a way to land a left hook and then another that put Martinez on the canvas before a frenzied capacity crowd at the UNLV campus arena. Martinez would go down one more time in the final round and was taking huge punches when the bell mercifully sounded to end the fight.

Martinez ended up winning a lopsided unanimous decision to regain the middleweight title. But the 12th-round rally by Chavez was one for boxing lore, reminiscent of a fight his father was in 22 years ago against Meldrick Taylor just a few miles away from the Las Vegas Strip.

“I was 20 seconds away from knocking him out. I started way too late,” Chavez said. “I didn’t really get started until the eighth round.”

Martinez was quicker, busier and far more accurate as he won round after round, piling up points as Chavez struggled to do much against him. Martinez said before the fight he didn’t consider Chavez a true champion and vowed to give him a beating he would long remember.

He did just that, to the point where trainer Freddie Roach told Chavez after the 10th round he was going to stop the fight if he didn’t do something spectacular.

“He fought a great fight and he was a lot tougher than I expected,” Martinez said. “He showed great heart.”

Martinez won 118-110 on two ringside scorecards and 117-110 on the third. Two judges had him winning every round until the 12th, while the third gave him only one round. The Associated Press had Martinez winning 118-110.

Chavez lost for the first time, falling to 46-1-1, while Martinez improved to 50-2-2.

The wild ending nearly ruined what was a great night for the Argentinian, who used his speed and boxing skills to dominate until the final round. Chavez was bleeding from the nose, his face was marked up and he looked finished until suddenly landing a huge left hook to drop Martinez for the first time.

Martinez got up only to take several more head punches and go down once again. Chavez kept after him when he got back up, trying desperately to land the finisher before the bell sounded and the decision was lost.

“If Julio wants a rematch, we’ll do a rematch,” Martinez said.