Saul "Canelo" Alvarez kept his WBC super welterweight title by knocking challenger Josesito Lopez down three times before stopping him late in the fifth round at the MGM Grand Hotel.

Mexico's Alvarez had Lopez bleeding from both the nose and mouth Saturday as referee Joe Cortez stopped the one-sided fight with five seconds remaining in the fifth round.

The 22-year-old Alvarez, who is notable for his red hair, freckles and thunderous punching power, made his fifth title defence against a gritty but overmatched American opponent.

"I am very happy with what I showed today," Alvarez said. "In boxing you are always learning and I still have a lot to learn. But I will be better next time. I want the big fights now — Cotto, Mayweather. I want them all.”

Alvarez was the more aggressive fighter from the opening bell in the 154-pound (70kg) fight as he kept his perfect record intact, improving to 41-0-1 with 30 knockouts.

He continually trapped Lopez on the ropes where he battered the challenger with multiple punch combinations that led to the knockdowns.

He floored Lopez down with a left hook to the body in the second round, again in the third and fourth and then put the finishing touches on with a right to the head in the final round that forced referee Cortez to step in.

Lopez, of Riverside, California, was fighting for a title for the first time in his career. He was a heavy underdog heading into the fight and it showed as he had lost every round on the judges' scorecards.

Lopez, who moved up in weight to fight Alvarez, dropped to 30-5 in his career. He said fighting at 154 pounds was too much for him.

"Canelo is a good fighter. He proved he is a better fighter," Lopez said. "It is way out of my weight. I felt good, but the size was different for me. He was much stronger. He’s a much better fighter than Victor. He has a lot of skill and he’s very smart. He’s the total package.”