Jermell Charlo KO's Brian Castano in 10th round for undisputed 154-pound world titles

CARSON, California – There's no debate who is the best junior middleweight.

Jermell Charlo and Brian Castano fought to a draw last year, but the American closed the show by way of 10th-round stoppage to become the undisputed 154-pound world champion before a crowd of 7,406 in a thrilling rematch on Saturday at Dignity Health Sports Park, otherwise known as "The War Grounds," in scintillating fashion.

“This is legacy,” Charlo, the WBC, WBA, IBF, and WBO titleholder, said during his post-fight interview on Showtime. “This was the fight of the year.”

Charlo started off by popping Castano with jabs and straight rights while keeping his back off the ropes, which he failed to do in the first fight. However, Castano used feints on the inside to connect a series of short rights that sent his opponent to the danger zone. By round 4, no one in the crowd was sitting down as the two best 154-pounders fired back with their best punches. Like their first encounter, Castano had the right hand, and Charlo had the devastating left hook.

Round 5 was a clear candidate for Round of the Year as Charlo and Castano continued to pound each other with thudding power shots that would normally result in a knockout.

Perhaps this was the kind of fight Charlo lured Castano into because by the seventh round, the Argentinian had slowed down considerably, and Charlo took advantage by timing him with jabs and power shots to the body and the head.

A left hook connected right on the button and dropped Castano like a lawn chair two minutes into the 10th round.

“I listened to my corner this time,” Charlo (35-1-1, 19 KOs) said. “I saw I was breaking him down, he was slowing down and I seen him crumble (when the hook landed). I knew it was over.”

Castano beat the count, but stumbled backward into the ropes. Referee Jerry Cantu had every right to stop it at that point, but he allowed the fight to continue. Within seconds, Charlo crumbled him with a left hook to the body, and Cantu waved the fight off at 2:33 of round 10.

“This is unbelievable,” Charlo said. “I gave it my all and that was the end result. I can consider this (fight) to be nerve-racking like my first fight, but I wanted to make sure this was my fight. The future is bright.”

Castano (17-1-2, 12 KOs) gave Charlo his props.

“Everything that was said outside of the ring was bull,” he said during his post-fight interview. “We were warriors here tonight.

“It was power back and forth, and then his [left hook] ended it. That’s the difference between this fight and the last fight, he got me.”

In the co-main event, Jaron "Boots" Ennis (29-0, 27 KOs) knocked out Custio Clayton (19-1-1, 12 KOs) in two rounds.