CARSON, California – The reality of what he had accomplished Saturday night started to set in as a contemplative Jermell Charlo reflected during his post-fight press conference on his 10th-round knockout of Brian Castano in their remarkable rematch.

A few days shy of his 32nd birthday, Charlo could call himself an undisputed champion, something only six other boxers in any division could claim during this sport’s four-belt era. By adding Castano’s WBO belt to his IBF, WBA and WBC championships, Charlo (35-1-1, 19 KOs) joined a prestigious group that also includes middleweights Bernard Hopkins and Jermain Taylor, junior welterweights Terence Crawford and Josh Taylor, cruiserweight Oleksandr Usyk and super middleweight Canelo Alvarez.

“I feel like I really accomplished something like very, very important, very, very major,” Charlo said, “something that’s gonna stand for a very long time. … I feel like I made it to a Hall-of-Fame level. I know hatin’-ass ESPN ain’t gonna believe this, but I made it to a very, very strong, a very, very strong pedestal in my career. You know what I’m saying? And so, I believe that like I get to call the shots, I get to do what I do. And who knows what’s next for me in boxing? You know what I’m saying?”

Unlike Crawford, Usyk and Alvarez – three of the last four undisputed champions – Charlo plans to defend his four titles in his next fight. Crawford, Usyk and Alvarez all moved up to the welterweight, heavyweight and light heavyweight divisions, respectively, for their first fights after becoming undisputed champions in the aforementioned divisions.

Alvarez, who was upset by WBA light heavyweight champion Dmitry Bivol on May 7 at T-Mobile Arena in Las Vegas, will move back down to defend his IBF, WBA, WBC and WBO 168-pound championships against Gennadiy Golovkin either in his next fight or his fight after what could be an immediate rematch versus Bivol.

Charlo, meanwhile, will have to make mandatory defenses against Russia’s Bakhram Murtazaliev (20-0, 15 KOs) for the IBF, Coachella, California’s Sebastian Fundora (19-0-1, 13 KOs) for the WBC and Australia’s Tim Tszyu (21-0, 15 KOs) for the WBO. Whoever wins the unscheduled elimination rematch between number one-ranked Israil Madrimov (8-0, 6 KOs) and second-ranked Michael Soro (35-3-1, 24 KOs) will become the WBA’s mandatory challenger for Charlo’s other title.

“I listened to my coach,” Charlo said in reference to Derrick James. “We gonna stick to the game plan, stay back in the training because we know we got mandatories, bro. When you become the top tier like this, you got all these sanctioning [bodies], everybody number one, everybody want a shot at the title. And it’s lookin’ good. But I’m busy. They gotta fight each other. They gotta fight each other. I’m busy. Right?”

Charlo knocked Argentina’s Castano (17-1-2, 12 KOs) to the canvas twice during the 10th round, when their “Showtime Championship Boxing” main event ended at Dignity Health Sports Park. Their first fight resulted in a controversial split draw nearly 10 months earlier, last July 17 at AT&T Center in San Antonio.

Keith Idec is a senior writer/columnist for He can be reached on Twitter @Idecboxing.