Tim Tszyu couldn’t help but chuckle at Jermell Charlo’s idea of a post-fight celebration following the biggest win of his career.

Houston’s Charlo emphatically laid claim to the undisputed junior middleweight championship following a tenth-round knockout of Argentina’s Brian Castano (17-1-2, 12KOs). Charlo won Castano’s WBO belt, adding it to his collection of the lineal/WBA/WBC/IBF titles to the division’s first-ever male boxer to own every major title in the four-belt era.

Following the fight, Charlo took exception to relayed previous comments from Tszyu that he was “a little bit soft” and “doesn’t bring the pressure.” Charlo dismissed the claims along with the questions asked by Fox Sports Australia’s Duncan McKenzie-McHarg, replying ‘F--- you and Tim Kazoo… it’s different heat over here in America, baby. It’s different heat in America.” Charlo also verbally sparred with at least one more reporter during the post-fight press conference following their Showtime main event Saturday evening at Dignity Health Sports Park in Carson, California.

“He’s such an angry person. He’s always frowning. He’s never happy,” Tszyu told BoxingScene.com. “He just won four belts and he’s there yelling at reporters. It’s your moment to celebrate, I don’t know he needs to be so angry and miserable.

Australia’s Tszyu (21-0, 15KOs) is the WBO mandatory challenger, a title defense that Charlo inherited with his win over Castano. Charlo also has outstanding mandatory title defenses with IBF number-one contender Bakhram Murtazaliev (20-0, 15KOs) and interim WBC titlist Sebastian Fundora (19-0-1, 13KOs).

However, it was Tszyu who allowed the Charlo-Castano rematch to happen for the undisputed championship. Tszyu’s team previously protested with the WBO to have his mandatory title status enforced, which would have forced Castano to either next face the unbeaten Australian or vacate. The matter arose after Castano withdrew from the scheduled March 19 bout with Charlo after suffering a slight biceps tear. Tszyu—who was due to face Terrel Gausha in the televised co-feature—offered to replace Charlo in the main event. His team also flagged how unfair it would be to wait even longer for a title shot, depending on the severity of Castano’s injury.

A deal was eventually reached that allowed Charlo-Castano II to proceed and for Tszyu to remain active. Tszyu—the son of Hall of Fame former lineal junior welterweight champion Kostya Tszyu—inked a multi-fight deal with Premier Boxing Champions (PBC). The deal began with a March 26 Showtime headliner where he overcame a first-round knockdown to outpoint Gausha over twelve rounds at The Armory in Minneapolis.

Tszyu made a point to fly in to attend the May 14 Showtime card in Carson, California. More so than getting a close view of his next opponent, he wanted to remind the eventual winner in Charlo of what is in his near future.

“Charlo can keep talking about Tim Kazoo, but he knows exactly who I am,” notes Tszyu. “Stop being so angry and going on your year-long vacation and get ready to fight me. If you don’t, then get ready to vacate your title.

“Either way, it’s my time.”

Jake Donovan is a senior writer for BoxingScene.com. Twitter: @JakeNDaBox