Jose Luis Castillo used his experience and superior strength to batter a game Julio Diaz Saturday, registering an impressive 10th round TKO to retain his WBC lightweight title at the Mandalay Bay in Las Vegas.

Castillo put Diaz down with a sharp left hook early in the round, then dropped him a second time with a right-left off the ropes. Diaz rose, but referee Richard Steele thought better of it and ended the fight.

In the end, Diaz’s face was a mess, with his left eye swollen shut and his right eye bruised. The resilient Castillo was unmarked.

“We had a plan and I was able to execute it,” said Castillo, who improved to 52-6-1 (46 KOs). “But he caught me a couple of times. I saw stars.”

Next for Castillo is a scheduled May showdown with Saturday's original opponent, Diego Corrales.

“In 15 days,” Castillo said, “I'll go back to the gym.”

It has been an incredible nine month run for the native of Sinoloa, Mexico, who won the vacant WBC 135-pound title in June with a decision over Juan Lazcano, defended it via decision against Joel Casamayor in December, and then defeated Diaz – the recently-stripped IBF champ – on Saturday night.

And he won just as his former employer and idol, Julio Cesar Chavez, used to notch victory after victory: with pressure, pinpoint punches and an undying belief in himself.

Through seven rounds, the fight was up for grabs, as the two lightweights battled on even terms, with Castillo landing well to the body and Diaz connecting with jarring left hooks to the head. An accidental clash of heads produced a cut above Diaz’s left eye in the fourth round, but that didn't seem to deter the Coachella, California, resident, who bothered Castillo by switching to southpaw every now and again.

But another cut in the seventh round did affect Diaz, and Castillo stepped up the attack. He weakened Diaz with sharp punches, and soon enough his left eye began to swell grotesquely. It might have been via a head butt or a punch, but Diaz was definitely receiving the worst of it.

By the 10th, Diaz, 30-3 (22 knockouts), was on his bicycle, just trying to figure how to avoid Castillo's punches with his eyes swollen practically shut.

Castillo wasted no time in cornering his opponent and stopping him.

“I couldn't see all his punches coming,” Diaz said. “He's a big lightweight. The biggest there is. I give him credit. He did a good job. It's a good experience for me. I'm still young.”

All three judges had Castillo ahead 88-83 at the time of the stoppage.

In the main support, Jeff Lacy from St. Petersburg, Florida, retained his IBF super middleweight title with a thrilling seventh round knockout of ultra-tough Rubin Williams. Detroit's Williams was stopped with a vicious assault, but Williams provided quite an account of himself, fighting off the ropes to rock the champion throughout the slugfest.

In the end, though, Lacy had too much speed and power.

Lacy improved to 19-0-1 (14 KOs) and looks forward to a possible December showdown with fellow 168-pound champ Joe Calzaghe. Williams falls to 26-2 (15 KOs), but his stock rose with his gutsy performance Saturday night.