Wladimir Klitschko's trainer Manny Steward says Dereck Chisora poses a big risk to the IBF/WBO world champion.
The Londoner takes on Klitschko in Germany on April 30.
And veteran trainer Steward says he would have preferred it had Klitschko not faced him.
"Chisora is the most dangerous opponent Wladimir will have fought in many years, because Dereck brings energy and confidence and youthfulness that's different from what we've been fighting in recent fights," he told Sky Sports Ringside.
"I think Dereck Chisora is a very tough fight. If it was up to me, I would not fight Dereck. I would prefer to fight with David Haye.
"But Wladimir has to make the decision.
"And Wladimir is an honorable man, and he felt that he should fight Dereck, because the way the fight was canceled because of his injury.
"It's not Dereck's fault, so he felt that he had the obligation to fight Dereck because it's going to be a long time between he and David Haye."