Ricky Hatton fears Tyson Fury may already have done "too much damage" to his career by the time he launches his comeback.
The heavyweight is preparing to return this summer having not fought since Nov. 2015 owing to numerous personal problems that had led to his boxing licence being suspended.
Fury won the IBF, WBA and WBO heavyweight titles when he outpointed Wladimir Klitschko to secure one of the finest ever victories by a British boxer before struggling with depression and admitting to using cocaine.
The 29-year-old also accepted a backdated two-year ban in December after UK Anti-Doping charged him with testing positive for elevated levels of the banned steroid nandrolone.
By the point of his planned return this summer, Fury will have been inactive for a similar period to Hatton prior to his own attempted comeback against Vyacheslav Senchenko in November 2012.
A struggling Hatton -- a former light-welterweight and welterweight world champion -- was defeated in that fight having also had to lose a significant amount of weight and battle depression, and he never fought again.
Hatton found he was no longer capable of fighting at the level that led him to such success, and of Fury he told PA Sport: "The one thing that worries me is in the two or three years he's had out, has he already done too much damage? If he'd fought Anthony Joshua maybe six, seven months after Klitschko, he'd have beaten him.
"Can he claw back the damage he's done with putting on the weight, and whatever's happened in his life, can he get that back? I don't know.
"It's very hard when you've been doing it for all of them years, and think 'Here we go again'. It's sometimes very hard to get motivated.
"I lost weight in the gym, in sparring I felt brand new, and then the minute the bell went on fight night, I went 'This ain't here no more'.
"Tyson's still relatively young in heavyweight terms, so hopefully it won't be for Tyson what it was for me. But sometimes you don't know whether it's gone until you get in there."
Hatton gambled in fighting a dangerous opponent like Senchenko when lengthy lay-offs are often followed by low-risk affairs. He was also trained by Bob Shannon for the first time, and Fury will similarly be working with the little-known Ben Davison despite the guidance of his uncle Peter Fury once being so influential.
"Maybe have a warm-up to shed a bit of ring-rust, but Tyson's got huge self-belief, and if he's going to lose seven stone, he's got to have an opponent in front of him to motivate him," Hatton, 39, added of his fellow Mancunian at the launch of new boxing tournament Ultimate Boxxer.
"It was only a few weeks ago he was in my gym. Even though he's still carrying a bit of excess, he looked sensational: blistering hand-speed.
"You're better when you look in someone's eyes and know they're throwing every punch with you, which is obviously what Tyson had with Peter. Tyson will be alright, but it's just a shame, family-wise, when they've had so much success together that it has to end.
"When you've got self-belief like Tyson has, it's very hard to beat a man like that.
"To have a Mancunian heavyweight champion of the world was absolutely brilliant."