Jack Loew told Steve Bunce's Boxing Hour that defeat for Kelly Pavlik is unthinkable against Marco Antonio Rubio on Saturday night.
Pavlik was conclusively defeated by former middleweight king Bernard Hopkins in a catch-weight fight in October.
The Youngstown fighter takes on Rubio in his home town live on Setanta Sports 2 from 2am on Sunday morning and will be seeking to prove he remains the world's best 11st 6lb fighter.
“It’s an important fight for Kelly," Loew said on Setanta Sports News.
"A loss at this point, right now, would be disastrous for his career. We’ve got to come out firing on all cylinders.
“I think he needs to have a very impressive win."
IBF champion Arthur Abraham is often touted as a future opponent for Pavlik. Loew insists they have tried to make this fight happen on many occasions in the past.
"We’ve offered him to over here and fight us, we offered to go to Germany and fight him there," Loew added. "We’re getting no response.
"Of course everyone’s saying we don’t want to fight Arthur Abraham. But we would be happy to fight Arthur Abraham in the States or in Germany.
"Once we get past Rubio we’ll probably go for [John] Duddy, providing Duddy gets past his opponent."
Duddy fights on the same night as Pavlik against Matt Vanda in a bout that will also be shown on Setanta Sports 2.
Finally, looking back on his charge's first defeat in October, although keen not to besmirch Hopkins' victory, Loew explained he would never again let a fighter go into a bout with the kind of problems Pavlik had with an elbow injury and flu symptoms.
"I do not want to take anything away from Bernard's victory," Loew said.
"I learned I would never put an unhealthy fighter in the ring again. We had an inflamed elbow he couldn't spar for three and a half weeks.
"He had a 111 temperature on the Tuesday before the fight, but we did not pull out so we have no excuses.
"If he was fit I'm not saying he would have beaten Bernard but you would have seen a very different Kelly Pavlik."