Canada's Custio Clayton suffers 2nd-round KO loss to Jaron Ennis

Jermell Charlo became the first undisputed super welterweight champion in the four-belt era when he stopped Argentina's Brian Castano in the 10th round of their rematch Saturday night in Carson, Calif.

After an outstanding bout with ample toe-to-toe action, Charlo (35-1-1, 19 KOs) dropped Castano twice in rapid succession in the 10th. Charlo leaped onto the ropes in celebration while the referee was still counting out his opponent, celebrating the addition of Castano's WBO 154-pound title to his WBC, WBA and IBF belts.

After unbeaten Philadelphia welterweight Jaron Ennis stopped Custio Clayton, of North Preston, N.S., with a vicious right hand in the second round of the show's penultimate bout, the main event was slightly delayed because Castano showed up late to the arena, according to the fight's promoters.

Ennis (29-0, 27 KOs) underlined his status as an elite welterweight with a violent victory in a meeting of unbeaten contenders. Clayton (19-1-1) went down in a heap after the chopping right hand from Ennis, and the Canadian stood on wobbly legs before the bout was waved off.

"I keep telling y'all every single time: We're in and out like a robbery," Ennis said. "We don't get paid for overtime."

After an impressive California debut, the 24-year-old Ennis is waiting for an opportunity take on elite welterweights like Errol Spence Jr., who attended this bout.

Charlo survived several impressive early rounds by Castano (17-1-2) in the rematch of the fighters' split draw 10 months ago in Texas. Charlo is only the seventh fighter to simultaneously hold every major title in any weight class since the four-belt era began in 1988.

Charlo, the Houston native and twin brother of middleweight champ Jermall Charlo, executed a