Jermall Charlo stays unbeaten with a knockout of Justin Williams

Already atop his weight class, Jermall Charlo spent months listening to Julian Williams saying the super-welterweight hadn’t fought anyone who justified the wearing of a world title belt.

The time for the response came Saturday in the ring, where Charlo knocked out Williams in the fifth round to retain his International Boxing Federation title at USC’s Galen Center.

Relying on hand-speed and reach advantages, Houston’s Charlo (25-0, 19 knockouts) sent Williams crashing to the canvas earlier in the fifth with a right uppercut squarely on the jaw.

Williams, who had also been sent down by a hard jab to the face in the second, was badly wobbled as he tried to stand in the fifth. Referee Wayne Hedgpeth allowed the fight to continue, but it wouldn’t last much longer.

“I trained hard for this fight, I stayed in the gym the whole time,” Charlo said. “No matter what, people have to respect my accomplishments. He just wasn’t on my level. I told everyone what I was going to do since the fight was announced. I knew I was going to win.”

Charlo pounced on the talkative Philadelphia challenger, handing him his first loss with a decisive combination closed by a left to the face that dropped Williams for good as Hedgeth waved it over 2 minutes 6 seconds into the round.

“He wasn’t too big, I just got caught,” a disappointed Williams said.

Williams (22-1-1) rested on a stool for an extended period inside the ring before he rose and walked to attempt to congratulate Charlo, who rejected the advance and drew roars of boos.

“I don’t want your congratulations,” Charlo said about the incident after having taken issue with Williams’ criticism that he’d beaten two over-the-hill foes, Cornelius Bundrage and Austin Trout, to become and remain champion.

The high tension evident in the post-fight incident bothered Andy Foster, the head of the California State Athletic Commission, who said he expected to fine Charlo and others on his side $2,500 for poor sportsmanship that include spraying water from a bottle.

Charlo and Williams ultimately embraced backstage and Charlo said he was sorry.

In undercard action, Florida’s unbeaten super-welterweight Erickson Lubin met the high expectations connected to him when he knocked out Juan Cabrera (23-2) of the Dominican Republic in the second round.

The 21-year-old Lubin (17-0, 12 KOs) varied the angles of his power punches in the first round, striking Cabrera from the gut to the face.

In the second, he first dropped Cabrera with a flurry to the head.

A combination of right hands to the head ended the bout at the 2:09 mark.

Ranked in the top five by two sanctioning bodies including the World Boxing Council, where Charlo’s twin brother Jermell is champion, Lubin said he’s aiming for a title shot in 2017. “He needs a few more fights, but he’ll be moving fast,” Jermell Charlo said during a Showtime interview.

Lubin also had interest in the Jermall Charlo-Williams fight. “I’m sitting ringside for this,” Lubin said.

Also, Riverside’s Josesito Lopez (34-7) won the opening bout by unanimous decision over Todd Manuel. The judges’ scores were 60-54, 60-54 and 59-55.

In an entertaining junior-welterweight bout, Russia’s Sergey Lipinets improved to 11-0 with his ninth knockout by stopping Australia’s Lenny Zappavigna in the eighth round.

lance.pugmire@latimes.com

Twitter: @latimespugmire