By Keith Idec

Matt Korobov isn’t a trash-talker.

The Russian southpaw prefers doing his talking in the ring. Jermall Charlo’s new opponent doesn’t think the unbeaten middleweight title-holder has quite done that during his rise toward the top of their division.

Korobov considers Charlo “a good opponent.” He just doesn’t know yet whether it’s accurate to include Charlo in the group of elite middleweights that features Canelo Alvarez, Gennady Golovkin, Daniel Jacobs and Demetrius Andrade.

“Those guys are not easy,” Korobov told BoxingScene.com on Monday, moments after signing a contract to challenge Charlo on Saturday night. “You know, it’s easy to say that you’ll fight them, but it’s never easy to fight them, exactly, when it happens. Those are the best guys in the division. He didn’t fight against them yet, so it’s just saying and not proving with your fights. With your job, you should do it in the ring.”

Korobov received this surprising opportunity to prove himself in the ring due to an adverse finding in a test sample Willie Monroe Jr. submitted recently to the Voluntary Anti-Doping Association. Al Haymon’s Premier Boxing Champions replaced Monroe with Korobov on Monday morning, once the WBC determined it couldn’t allow Monroe to challenge Charlo because Monroe violated terms of the WBC’s “Clean Boxing Program.”

“I just look at him as a good opponent,” Korobov said. “I’m just focusing on the things I have to do to win this fight. So I don’t think about what he’s gonna be. He was preparing for Willie Monroe. Of course, he is a southpaw, like me. But, you know, I have some keys against him and [Monroe is] definitely a different style than me. So I’m looking very forward to winning this fight.”

The 35-year-old Korobov was scheduled to battle Colombia’s Juan DeAngel (21-9-1, 19 KOs) in an eight-round, 162-pound bout on the Charlo-Monroe undercard. By preparing for that bout, Korobov is at least in shape for a difficult fight he accepted on less than one week’s notice.

Houston’s Charlo (27-0, 21 KOs) will make the make the first defense of his WBC interim middleweight title versus Korobov (28-1, 14 KOs). Their 12-round, 160-pound championship match will headline a PBC tripleheader that’ll air on FOX on Saturday night from Barclays Center in Brooklyn.

Jermell Charlo (31-0, 15 KOs), Jermall’s twin brother, is set to defend his WBC super welterweight title against Detroit’s Tony Harrison (27-2, 21 KOs) in the 12-round, co-featured fight. The telecast also will feature Dominic Breazeale (19-1, 17 KOs), of Eastvale, California, and Miami’s Carlos Negron (20-1, 16 KOs) in a 10-round heavyweight fight.

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