LAS VEGAS — Rising Mexican star Canelo Alvarez landed the heavier punches and more of them Saturday night, defending his 154-pound title with a lopsided decision win over an aging Shane Mosley.

Alvarez shook off a cut over his left eye from a head butt in the third round and dominated the fight, landing big punches to the body and occasional uppercuts to the head. He won all rounds but one on two scorecards, and all but two on the third.

It was the fourth defense for Alvarez of his 154-pound title, and Mosley gave it his best. But at the age of 40 he simply didn't have the reflexes or strength to be competitive against the 21-year-old champion.

Two judges scored it 119-109, while a third had it 118-108. The fight was on the Floyd Mayweather Jr.-Miguel Cotto undercard.

"It was a great experience," Alvarez said. "I felt really good and I want to thank Shane for giving me the experience."

Mosley hasn't won a fight in three years, losing five of his last seven. Mosley was trying to resurrect his fading career after losses to both Mayweather and Manny Pacquiao, but he came into the ring a decided underdog against Alvarez, who is considered one of the top young fighters in the sport.

"His defense is very good. He's really fast, and he can go a long way," Mosley said. "When the kids start to beat you up, it might be time to start promoting."

Mosley, whose pro career dates back to 1993, moved forward the entire fight and tried to keep Alvarez off balance with flurries. He took punishment throughout and appeared hurt by shots to the body in the eighth round.

But Mosley (46-8-1) never went down and was still fighting hard in the12th round, though by then the fight had already been decided.

"I didn't expect him to be that fast or that good," Mosley said.

Alvarez, who remained unbeaten in 41 fights, said he tried to knock Mosley down every round, but was never able. Mosley has never been stopped in a fight.

"I tried to knock him out, he took a lot of punches, but it didn't work," Alvarez said.

Alvarez said he wasn't sure who he would fight next, though the win puts him in the upper echolon for fights against Mayweather or Pacquiao.