Just like Oleksandr Usyk, Roy Jones Jr. understands the rigors of moving up in weight for a shot at a heavyweight championship against a bona fide big man.

Jones will argue that his ascent, which culminated in a 2003 WBA heavyweight title victory over John Ruiz, was an even more monstrous challenge than Usyk’s attempt to stand as undisputed heavyweight champion against unbeaten Tyson Fury on Saturday in Riyadh, Saudi Arabia.

Jones launched his Hall of Fame journey to become a four-division champion when he started his pro career as a junior middleweight 14 years before defeating Ruiz.

“It’s a very daunting task, but [Usyk] started heavy [as a cruiserweight]. I started at junior middleweight. There’s a difference,” Jones told BoxingScene on Thursday. “It’s not impossible for him to do, but Tyson Fury is [bigger] and [6-foot-9].”

And that means Usyk (21-0, 14 KOs) has to execute a vigorous challenge to deal WBC titleholder Fury (34-0-1, 24 KOs) his first defeat.

“I like Usyk because he’s dangerous, he’s creative and he’s never been beaten,” Jones said. “It’s to Usyk’s advantage that Tyson Fury didn’t look so good last time out [when he was knocked down by former UFC heavyweight champion Francis Ngannou].

“That gives Usyk more confidence now that Usyk has seen Fury can be beaten if you do the right things. However, when it’s a small man against a big man, the big man usually wins. It all depends on how bad Usyk wants it. It looks like he’s put on the right weight, the right muscle, and he’s the right size, so now we’ll see what happens.”

Jones said he’ll be watching closely to see if the 6-foot-3 Usyk can do two things:

“Can Usyk get around that jab? And can Usyk make his punches meaningful?” Jones asked.

“Usyk has to get beyond Tyson Fury’s jab because [of] Fury’s [height advantage] and he has a helluva jab. If Usyk can get beyond it, how much damage can he inflict? Because if he can’t get past the jab, he can’t win the fight. Once he does, and he can inflict damage, then we’ve got a fight. If he can’t, then it’s a long night for him.”

While former heavyweight champion George Foreman told BoxingScene on Wednesday that he believes Fury has been left susceptible to knockdowns after suffering five of them since his 2018 draw against Deontay Wilder, Jones counters that Usyk has “never been known as a devastating puncher like those guys.”

Where Usyk might possess an advantage, Jones thinks, is in his limited English.

While Fury has repeatedly labeled the former Olympic gold medalist and undisputed cruiserweight champion as a “sausage” (and far worse phrases), Usyk has maintained a stone-faced expression.

“I don’t think [mind games] work with Usyk because he doesn’t understand none of it,” Jones said.

As for the rematch clause that has Fury and Usyk headed to a mid-October second fight despite who wins Saturday, Jones said this historic crowning of the first undisputed heavyweight champion of the four-belt era is highly meaningful.

“This fight does matter because we’ll find out how good they are,” Jones said. “If Fury loses this fight, he’ll make adjustments. Same with Usyk. The second fight will really show who the best fighter is, but we won’t know until the first fight who’s going to jump out on top as the better fighter.”

Fury’s frame for this fight is far slimmer than in recent times, and Jones assesses that it’s a result of Fury’s flat showing against Ngannou, who was promptly destroyed via second-round knockout by former heavyweight champion Anthony Joshua in his next boxing match.

“What [Fury’s] got to be thinking is that he didn’t get in the right shape against Ngannou,” Jones said. “Therefore, he didn’t look the way he wanted. This one, he understands he can’t play games. This guy can box. Now [Fury’s] fighting a seasoned veteran who has skills.”

Jones spoke to BoxingScene while promoting a June 28 fight card on BLK Prime; he is sending three fighters he trains, including Andrew Murphy and Mandeep Jangra, to Legends Casino for the card in Toppenish, Washington.