PHILADELPHIA – Teddy Atlas considers Artur Beterbiev and Adonis Stevenson vastly different types of opponents for Oleksandr Gvozdyk.

Atlas acknowledged, though, that one important thing will remain the same for Gvozdyk versus Beterbiev as it was when he defeated Stevenson 10 months ago. Beterbiev, like Stevenson, is such a devastating puncher that Gvozdyk cannot afford to make a single tactical error in their light heavyweight title unification fight Friday night.

“There’s no room for mistakes,” Atlas told a group of reporters Wednesday at the Renaissance Philadelphia Airport Hotel. “There’s gotta be full concentration for 36 minutes, full concentration. And you have to fight one round at a time, one three-minute round at a time. Not [two] minutes and 59 seconds. No, not when you’re in there with a puncher that can change everything in a moment with one punch, as Stevenson almost did in the 10th round.”

According to Atlas, Stevenson nailed Gvozdyk with only one flush punch throughout a fight Gvozdyk won by 11th-round knockout December 1 at Videotron Centre in Quebec City, Canada.

Atlas believes Gvozdyk withstood that shot in the second round because the unbeaten Ukrainian saw it coming. Stevenson was able to hurt Gvozdyk with another left hand that knocked him into the ropes at the midway mark of the 10th round because Stevenson hit him with a punch that caught Gvozdyk off guard.

“The reason why he’s a champion is because he was able to handle that and able to survive that,” Atlas said. “That’s why he’s a champion. I mean, you could look at all the other rounds and say, ‘He’s a champion because of this. He’s a champion because of that. He gave angles. He used the jab. He punched at the right time.’ But he’s a champion because when the moment came, he behaved like a champion. And I have no doubt that when that moment comes [Friday night], he’ll do the same thing.

“But I’m just hoping that particular kind of moment doesn’t come, because we’ve trained to be very aware, as we did for the Stevenson fight, that there is no margin for error. There’s no margin for lapsing or drifting for a split second. Not when you’re in with a guy who can punch with the right hand the way that Beterbiev can punch with that single punch. So again, it’s never comfortable to be facing a puncher. But at least we know we’ve done it, and we know what it takes.”

Gvozdyk responded in the 11th round by buzzing Stevenson with a right hand. He sent Stevenson to the canvas with another right hand that ended their scheduled 12-rounder with 11 seconds to go in the 11th round.

The 32-year-old Gvozdyk’s victory over Stevenson (29-2-1, 24 KOs) clearly is the most noteworthy win of his five-year professional career. Stevenson suffered brain damage as a result of that knockout defeat, but the Quebec-based boxer is on the road to recovery.

Gvozdyk (17-0, 14 KOs) is a slight favorite to beat Beterbiev (14-0, 14 KOs), who owns the IBF light heavyweight title. ESPN will televise their scheduled 12-round fight as the main event of a doubleheader scheduled to begin at 10 p.m. ET/7 p.m. PT from Temple University’s Liacouras Center.

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