CARSON, California – If Jermell Charlo wants to keep all four 154-pound championships he now owns, he’ll have to make one of his mandated defenses against Tim Tszyu.

Australia’s Tszyu is the WBO’s number one contender for the junior middleweight title Charlo won from Brian Castano on Saturday night at Dignity Health Sports Park. Tszyu attended their memorable battle, which Charlo won by 10th-round knockout, and expressed his willingness to challenge Charlo next.

Tszyu stepped aside to allow another full title unification bout between Charlo (35-1-1, 19 KOs) and Castano (17-1-2, 12 KOs), but it isn’t clear who Charlo will fight next. Charlo came into his first fight with Castano, a controversial split draw last July 17 at AT&T Center in San Antonio, with an overdue defense owed to the IBF’s number one junior middleweight contender, Russia’s Bakhram Murtazaliev (20-0, 15 KOs).

Regardless, Charlo wasn’t the least bit interested in discussing a fight versus Tszyu (21-0, 15 KOs) during his post-fight press conference Saturday night. Houston’s Charlo took exception to a line of questioning from FOX Sports Australia’s Duncan McKenzie-McHarg, who relayed while presenting his first question about Tszyu that Tszyu called Charlo “a little bit soft” and claimed he doesn’t “bring the pressure.”

“F--- you and Tim Kazoo,” said Charlo, who seemed to intentionally mispronounce Tszyu’s last name. “Change the mic. Like stop asking me questions, dude. Clown-ass joke.”

Before the contentious conclusion to their exchange, Charlo indicated that Tszyu, who would take a significant step up in class to fight him, isn’t ready for that type of test.

“Hey, it’s different heat over here in America, baby,” Charlo said. “It’s different heat in America.”

Derrick James, Charlo’s trainer, also made it clear that Tszyu isn’t capable of competing at Charlo’s level. James, who also trains IBF/WBA/WBC welterweight champ Errol Spence Jr., was more diplomatic, though, about a possible Charlo-Tszyu fight.

“Well, I saw him his last fight,” James said. “He should be quiet. He didn’t really look [good]. I don’t really watch a lot of boxing, but I did see him and he didn’t look so great. So, I mean, there’s nothin’ to answer, nothin’ to answer. He didn’t look so great the last time. He should work on his own situation.”

The 27-year-old Tszyu got off the canvas in the first round of his last fight to defeat Terrell Gausha on points. Tszyu, a son of retired 140-pound champion Kostya Tszyu, defeated Cleveland’s Gausha (22-3-1, 11 KOs) by unanimous decision in a 12-round bout Showtime televised March 26 from The Armory in Minneapolis.

Unless Charlo vacates one or more of his titles, he will have to face the WBC’s mandatory challenger, interim champion Sebastian Fundora (19-0-1, 13 KOs), in addition to Murtazaliev and Tszyu. Whoever wins the WBA elimination rematch between number one contender Israil Madrimov (8-0, 6 KOs) and second-ranked Michael Soro (35-3-1, 24 KOs) willS become the WBA’s mandatory challenger for Charlo’s WBA belt as well.

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