Callum Smith has questioned whether George Groves still has the hunger and if hard fights are catching up with him ahead of Friday's world title bout.
WBA world super-middleweight champion Groves will make his third title defence after a ten-year career featuring three defeats, two by stoppage to Carl Froch and one on points to Badou Jack.
Groves (28-3, 20 KOs), 30, has also suffered injuries, needing surgery to repair a dislocated left shoulder sustained in his points win over Chris Eubank Jr in February.
He also broke his jaw last year and unbeaten Smith (24-0, 17 KOs), 28, believes he is the fresher and hungrier fighter.
"Some of the fights he's had will have made him a better fighter, but also put a lot of miles on him," Smith told ESPN.
"There's a big difference between us. He's had a harder career than me, he's picking up injuries and he's older. He's achieved a lot but I've yet to do it. It will be interesting.
"He's had a lot of hard fights, been stopped, but I've not lost. His hunger might not be what it was. He's looking for a few more fights to earn money and get out."
The English rivals face each other in the final of the World Boxing Super Series (WBSS), an eight-man elimination tournament, at the King Abdullah Sports City, Jeddah in Saudi Arabia.
Holding a much-anticipated fight between two popular English boxers thousands of miles away from home has raised eyebrows and just one British reporter from the mainstream media will be there.
Smith is critical of the decision to stage the fight outside England, but says fighting Groves is the reason he entered the WBSS.
"The tournament has been brilliant for me, and I've got a world title shot out of it, but I do believe the final being in Jeddah is a bit harsh on the fans," Smith told ESPN.
"It's a big domestic world title fight but only a handful of fans will get to watch it live and it's a downer. They will have to watch it on TV.
"It will be strange. It's going to be the same for him as well, it will be not be as good an atmosphere as it should be.
"I'm just pleased George Groves is in the other corner because this is the one I wanted right from the start, a chance to become world champion.
"I've got a lot to gain from beating Groves. He was the main reason I entered the tournament because he's got the world title."
The fight was delayed from May and then June because Groves needed more time to recover from surgery on his shoulder, which he dislocated in the last round of his win over Eubank Jr, of England.
Smith, however, is not banking on Groves suffering a recurrence of the problem.
"I've no idea whether the injury will be a nagging concern for him," Smith told ESPN.
"I can't go in expecting a below-par George Groves or that perhaps he will be injured on the night.
"I don't feel he would come back if he wasn't in good fighting shape. I'm expecting the best George Groves."