Haye (right) is 10 years Barrett's junior
British heavyweight hope David Haye says he will probably quit boxing if he loses to American Monte Barrett at London's O2 Arena on 15 November.
And Haye admits the fight is a "massive gamble" which could "go pear-shaped, violently, inside five seconds".
"If I can't get through Monte, I'm definitely not going to be able to beat Wladimir Klitschko, so I'll probably call it a day," added Haye, 27.
"If I stumble at the first hurdle I'll look a joke, so what's the point?"
Former undisputed cruiserweight champion Haye, who has one defeat from 22 fights, added that he was "looking forward" to finding out if he can take a punch from a seasoned heavyweight.
"You can either take it or you can't," said the Bermondsey fighter. "You can have all the skills in the world but if your punch resistance isn't there, it's not there.
Let's get it over and done with nice and quick and find out whether I'm the goods or not
"In the first couple of rounds I'm going to get a couple of guns bouncing off my chin and how am I going to react?
"Some people think I'll fall down and go to sleep, but I think I'll be able to tough it out and come through.
"But that's what it's about. I keep saying I want to be the best in the world and I want the biggest guys out there but I've got to get through this guy.
"It's the gamble that's going to get people interested, they don't have to wait 10 fights before I fight someone half-decent.
"I don't want to waste anyone's time. If I can't take it, I might as well find out now - what's the point in me dragging it out against a load of bums and then getting in there against someone like Klitschko and being found out?
"I'd rather find out here than get the whole British public behind me before letting them down. Let's get it over and done with nice and quick and find out whether I'm the goods or not.
"But I'm positive my hand will be raised at the end of the night. Being up at heavyweight will make a big difference. It's no secret I've always struggled at cruiserweight. The bigger I am the better I'll be able to take the shots."
The 37-year-old Barrett has lost six of his 40 fights, including world title challenges against WBA heavyweight champion Nikolay Valuev in 2006 and then WBC champion Hasim Rahman in 2005.
The New Yorker was also beaten by Wladimir Klitschko in his only fight in the United Kingdom in 2000.
"When I saw David I thought, he's competitive, explosive, I want to fight the guy, but I never thought in a million years he'd take the fight," said Barrett.
"It's a gamble for him because I'm dangerous and they don't know which Monte is going to come into the ring.
"Is the inconsistent Monte coming? Is the Monte who's starving and struggling to feed his kids coming? Is the Monte who's got a lot of issues coming?
"But at the moment I'm destroying all in my path, and on 15 November the real Monte Barrett will come to the ring."