Tony Bellew claims he would have been "haunted" had he turned down undisputed world cruiserweight champion Oleksandr Usyk's challenge ahead of this weekend's showdown.
Bellew was seemingly on the verge of retirement after burnishing his legacy with a brace of stoppage victories over British rival David Haye in his two most recent outings.
Usyk, though, called out Bellew immediately after triumphing in the World Boxing Super Series to unify the WBC, WBA, IBF and WBO titles at 200lbs.
The unbeaten Ukrainian, who also holds the prestigious Ring Magazine belt, is arguably the most formidable opponent of Bellew's career.
Usyk v Bellew: Tale of the tape & big-fight details
- Fight night: Saturday November 10
- Titles: WBA, WBC, IBF & WBO Cruiserweight titles
- TV Channel: Sky Sports Box Office (£19.95)
- TV Start time: Undercard from 6pm, Main event approx 10 GMT
- Radio coverage: BBC Radio 5 Live
- Venue: Manchester Arena
- Sky Bet odds: Usyk 1/8, Bellew 4/1, Draw 33/1 (Click to bet)
But the prospect of becoming the first Briton to hold all four major world titles simultaneously proved too tempting to turn down for the Liverpudlian.
Bellew, himself a former world cruiserweight champion, said: "When he had all those four belts round his waist the first name out of his mouth was me. I couldn't believe it, I'm genuinely still shocked.
"If it was about money I could have fought a much lesser fighter and earned much more. I took this fight - it is the biggest challenge of my life. I've always known, deep down, I could become a world champion with the right scenario.
"When I left the cruiserweight division I felt I was the best cruiserweight in the world.
"Make no mistake, I could lose on Saturday night. If he is as good as everyone thinks he is then I could lose. I have no problem with that.
"But what would have haunted me much more was if I had stayed retired, and then when he calls my name with all those belts on, if I'd walked away that would have haunted me.
"I'm here now and I'm competing in a fight I never thought would be possible. I'm truly living the dream, fighting for the WBC, WBA, IBF, WBO and this little bad boy (Ring Magazine belt).
"It's unbelievable. From where I've come from it's an impossible dream. I never thought this would happen."
Bellew came in at 199.4lbs at Friday's weigh-in, one pound heavier than his opponent at the Manchester Arena on Saturday night.
The build-up to this event has seen none of the histrionics that have occasionally overshadowed Bellew's bouts, and the respect between the pair was palpable at the weigh-in.
The two shook hands before engaging in the staredown, Bellew covering the lower part of his face with a scarf and Usyk doing likewise with a Manchester City scarf.
"He doesn't speak good enough English that I can banter with him, get him going," Bellew added.
"I won't lie, I would if I could! I like a bit of back and forth but ultimately I admire him. I have no bad words for him - it is unusual for me to give a man so much credit.
"I am always confident. It has been a long camp but I have been very diligent in how I've prepared. Making the weight was not a problem."
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