Antonio Margarito proved he was ready for the best. Kermit Cintron proved that he wasn’t ready.

Margarito overwhelmed previously undefeated Cintron Saturday at Caesars Palace in Las Vegas, cutting him early and stopping the powerful-but-inexperienced challenger in the fifth round to retain his WBO welterweight title.

Margarito dropped Cintron twice in the fourth round and again in the fifth before the bloodied Puerto Rican sharpshooter’s corner stopped the fight at 2:12.

With the win, Tijuana’s Margarito bolstered his claim as recognized champion Zab Judah’s top challenger – calling him out along with Oscar De La Hoya and undercard winner Shane Mosley.

“We knew he was a heavy puncher, so we took our time and picked our punches,” Margarito told ESPN’s Jeremy Schaap after the bout. “We’re ready for fights with Mosley, De La Hoya and Judah.”

Margarito improved to 32-4 (22 knockouts) and looked like one of boxing’s more underrated champions with his impressive knockout Saturday.

Both punchers started cautiously before Margarito began connecting with his jab in round two. Cintron (24-1 22 KOs) landed a right hand that stunned Margarito in that round, but he would soon be met with a furious assault.

Things started going badly for Cintron in the third round, when a cut appeared over his left eye.

Margarito hurt Cintron with a huge uppercut at the end of the third, which set up the violent fourth. Margarito landed a counter right-left followed by a right to the body and attacked with fury as Cintron tried in vain to cover up. He finally hit the deck.

He rose, only to be met again with more punches, and he was dropped again.

Cintron showed guts just lasting through the round.

Margarito wasted little time going after his wounded prey in the fifth, and Cintron tried to hold on as he staggered around the ring on wobbly legs. A short right hand put Cintron down again. And he got up again.

But his legs were history, and a Margarito volley, capped by a push, put Cintron on his behind again. He found his feet, but his corner wisely threw in the towel and referee Kenny Bayless stopped the slaughter.

Afterwards, Cintron was a picture of despair and disappointment, crying in the ring.

“I was operating with one eye, and it kept bothering me,” he told Schaap. “I’ve spent five years in this sport, and look how far I got. (But) he was strong. He kept coming forward. It just didn’t go the way I wanted it to go.”

It was an emphatic end to a thrilling night of boxing.

In the main support, three-time world champ Mosley had to work perhaps harder than expected, winning a tough unanimous decision over previously unknown David Estrada of Chicago.

It was Mosley’s first welterweight fight since 2002, when he dropped a decision to archrival Vernon Forrest. And while Mosley, 40-4 (25 knockouts), won comfortably by scores of 97-93, 98-91 and 99-91, he appeared to lack some of his old magic.

Mosley struggled to establish himself early – before a vicious body attack in round four turned the tables. “Sugar” doubled Estrada over with a left to the liver, and though Estrada was game in lasting the distance, he never quite recovered.

Mosley swept the final five rounds. His reflexes were sharp and his old speed appeared to be intact, but the Pomona, California native appeared overanxious at times – wanting to load up on big punches rather than take his time.

But it was a good win for a fighter who hadn’t won in almost two years. He suffered back-to-back losses to junior middleweight champ Winky Wright.

Mosley said the weight felt good and he was pleased with his performance: “I don’t have to overexert myself to get a guy’s respect.”

He also gave Estrada (18-2 9 KOs) credit.

“I tip my hat to him,” Mosley said. “He’s a very tough fighter.”

And, in an exciting heavyweight contest, undefeated Calvin Brock got up off the canvas to upset contender Jameel McCline, winning a unanimous 10-round decision.

Brock, (25-0 20 KOs) showed smooth boxing skills, good power and great courage in rising from a wicked seventh round left hook that flattened him. He boxed neatly the rest of the way to win by scores of 96-94, 96-93 and 97-93.

“McCline was a lot better than I thought,” Brock said.

“He's a good fighter,” McCline said about Calvin Brock.