Boxing:Defeat by Paulie Malignaggi on Saturday night in their light-welterweight contest in Las Vegas would spell the end of Ricky Hatton's career, according to British heavyweight David Haye.
The 30-year-old Mancunian is facing his first real test since losing his unbeaten record to Floyd Mayweather Jr last year.
Haye insists it's a make-or-break fight for Hatton.
"If he loses this fight then I think his time as a big-time fighter and fighting at this level is probably over," Haye told BBC Radio Five Live.
"If he can't beat a Paulie Malignaggi then I'd say what's the point, really. But if he does beat him he could be looking at another mega fight with the winner of Oscar de la Hoya and Manny Pacquiao.
"That's about as big as you're going to get in boxing."
Hatton is famous for his fun-loving lifestyle and often piles on the weight between fights, something Haye believes does him no favours, though he has been impressed by the Mancunian's preparation for the Malignaggi fight under the guidance of new trainer Floyd Mayweather Sr.
"I think it's great (Hatton working with Mayweather), I really do," added Haye. "You always worry about Hatton when you see him between fights.
"How does he abuse himself that badly and then get back in such tremendous shape? There's got to be a knock-on effect.
"But if he's hooking up with Floyd Mayweather Sr, I know for a fact this guy's serious about his boxing. He'll have Hatton living and breathing boxing.
"He'll have him up early in the morning, he'll have him going to bed early at night. He'll be with him at every training session.
"The stuff I've seen from him in the build-up looks really good. He's actually getting Hatton's head moving, which is something that's stopped happening in recent fights, and he's looking back to his best."
Haye, a former multiple world champion at cruiserweight, announced his arrival in the heavyweight category with an impressive stoppage of Monte Barrett in London last weekend.
He is now hoping to challenge one of the dominant Klitschko brothers, and revealed WBC champion Vitali is his most likely opponent.
"Vitali was actually at my fight," said Haye. "He's looking at me seriously as an opponent and that's really nice to see.
"I've run around in the past chasing Wladimir because Vitali was retired for a while and it looked like that's the brother I was going to fight but … they seem to have put the bigger, tougher brother in front of me.
"That's fine by me, if that's the Klitschko brother I'm going to get then bring it on."