Top Rank president Todd DuBoef warns that it would be a big mistake if Devin Haney overlooks his upcoming opponent, Vasiliy Lomachenko.

On Saturday night at the MGM Grand in Las Vegas, Haney will defend the WBA, IBF, WBO, WBC lightweight titles against Lomachenko.

Lomachenko, a former three division champion and a two-time Olympic gold medalist, believes that he's in the best shape of his career.

Besides the undisputed crown at 135-pounds, the winner could land Shakur Stevenson.

"Loma says he is 100 percent and the finest he could be. So if Haney can take out Lomachenko at his finest, I think that is a very, very big mark for Devin to accomplish," DuBoef said to Sky Sports.

"Devin, we've seen, he's got great size, great speed, good footwork, really quick hands. But this is the matrix, you do not know what you're in with. He's going to learn a lot on Saturday night, if he hasn't already. Because he's going to get a masters degree from one of the great fighters of our era. Listen, absolutely [Stevenson to face the winner makes sense].

"So I think from a pure boxing perspective, to see Devin and Shakur is a natural, natural fight. It would have been like Mayweather and Mosley in their prime, which we didn't get. It's that type of fight, and they know each other well. Love to do those type of fights, but we'll see what happens with the outcome and how both fighters feel, and how Lomachenko feels. We have to read the room a little better and decide to make moves with the fighters, rather than force something they don't really want."

Most observers view Lomachenko as being on the slide, and Haney being on the rise.

Win or lose, Duboef believes Lomachenko will be by far the biggest test of Haney's young career.

"That's a big mistake [to write off Lomachenko]," Duboef said.

"It's easy, it's like you've got the new shiny car and jump on, but forgot about that workhorse that was just so beautifully driven for a decade. You just forget so quickly.

"I would not forget Loma. He does things in the ring that we have never seen. The footwork, the ability to throw punches from all these different angles. And I'm not sure Haney has seen anything like this, because most fighters haven't seen what Loma can do."