Former world champion Joe Calzaghe believes Tony Bellew wastes too much energy with his hatred of cruiserweight rival Nathan Cleverly.
Cleverly beat Bellew in 2011 to retain his WBO light-heavyweight title, but both have moved up to cruiserweight since then.
Bellew claims he "hates" Cleverly, his opponent in a rematch in Liverpool on 22 November.
"Anger burns off too much energy," Calzaghe said.
"He looks like he legitimately hates Nathan which is not really a good thing if you go into a fight and you burn up a lot of energy.
"You have to be cool, calm and collected. Nathan, of what I've seen of him, is calm.
"When you go into a big fight and a needle match, like I've done myself in the past, you need to keep yourself calm."
Bellew has previously suggested defeat could force the loser to quit and Cleverly has said he could retire if he loses.
Former undefeated world super-middleweight and light-heavyweight champion Calzaghe says the bout at the Echo Arena is "make or break" for both fighters.
"It's a huge fight for both fighters," Calzaghe added.
"Bellew's a good fighter, take nothing away. He can punch, he's strong and he's obviously 100% focused for this fight.
"But I just think Nathan, if he sticks to his game plan and fights a clever fight and uses his speed, he will definitely win this fight.
"I've seen Nathan train and he's in tremendous condition.
"He's 100% confident and why shouldn't he be - he's beaten him once."