James DeGale has said Chris Eubank Jr. is "too arrogant" to benefit from using a full-time trainer for the first time.
Former IBF world super-middleweight champion DeGale faces his English rival at The O2 in London on Saturday in a fight neither can afford to lose.
Eubank (27-2, 21 KOs), 29, decided to employ a trainer for the first time after he was out-pointed by George Groves for the WBA world title a year ago.
Previously, Eubank organised his own training schedule, took advice from his father and former world champion Chris Eubank Sr. in the corner during fights and relied upon his father's old trainer, Ronnie Davies, as an adviser.
American Nate Vasquez will work in Eubank's corner on Saturday, after the pair met at Floyd Mayweather Jr.'s gym in Las Vegas last year, but DeGale (25-2-1, 15 KOs), 33, is unconvinced it will lead to a fundamental change in how he will fight.
"I expect him to be better than he was against Groves, but his coach won't help him because he's too arrogant to listen to anybody," DeGale told ESPN. "When things go down after six rounds, he will revert to type and go back to doing what he always does. He's not going to suddenly change into a different fighter.
"The difference between me and Eubank is I've been there and done it, I'm tested, I'm proven, I've won an Olympic gold medal and been a world champion," DeGale said. "But he has done nothing in this sport."
Londoner DeGale wants to fight more on home soil after just one UK performance in the past four years.
With Groves recently announcing his retirement, the other big domestic dust-up available for DeGale is against WBC champion Callum Smith. But Smith has recently been linked to a move up to light heavyweight and Eubank could realistically be the last big, domestic duel available to DeGale, who lost a tight majority decision to Groves in 2011.
DeGale certainly cannot afford another off-night like the one he had in December 2017, when he lost the IBF world super-middleweight title in a fourth defence to American Caleb Truax on a majority decision.
DeGale won back the belt in a rematch last year and now wants to silence Eubank, who claims he got the better of him in a 2012 sparring session.
"He has run his mouth for a long time, since he said he schooled me in that sparring session, which is a joke," DeGale said. "I know what really happened in that sparring session, but it makes for an interesting fight now.
"I call these the legacy fights. People will remember you for domestic grudge fights like this, and these last few fights will be at home. I've fought in America, now it's time to take it home.
"It could have been a big fight with Groves, but he's won his world title, he had been looking to retire, he fulfilled his dream and it must be the right time for him," DeGale said. "Going by my recent performances people are saying I'm in decline, which I get, but I'm in great shape and I've still got a couple of years left and I still have big fights left here."