Lacy is unbeaten in 19 professional fights

Castillo stopped Julio Diaz in the 10th to retain his WBC lightweight title.

"I just did what I knew I had to do, put the pressure on and throw a lot of punches," said Castillo. "I really didn't feel his punches at all."

Fighting on the undercard, Lacy defended his IBF super middleweight title with a seventh-round stoppage of Rubin Williams.

Lacy, now unbeaten in 19 professional fights, had to take some decent shots from Williams early in the fight.

But his class soon told and referee Tony Weeks had no choice but to call an end to the bout early in the seventh.

"I wasn't looking for the referee to stop it, I wanted to make him want to stop it," said Lacy.

"As the rounds went by I got stronger and stronger.

"He was determined. He was a bad boy. I have to admit he has a great chin, but I can dish it out and I can take it."