That is according to former cruiserweight world champion Johnny Nelson.
Bellew will trade blows with Usyk this evening, vying to take the Ukrainian’s cruiserweight belts and become undisputed world champion.
It is the first time such a bout has taken place in the United Kingdom, and 20,000 people will watch history unfold at the Manchester Arena.
Bellew’s ascent has been quite remarkable since he moved up from light heavyweight in 2013 after a crushing knockout loss to Adonis Stevenson.
After claiming the WBC cruiserweight strap at his beloved Goodison Park, The Bomber then defended his title and beefed up to defeat David Haye twice at heavyweight.
This fight against the genial Usyk (15-0) is the Liverpudlian’s toughest yet, and the away fighter is the 1/6 favourite.
Nelson defended his WBO 200lbs belt for six years before retiring in 2005, and he believes a Bellew win would rank among the greatest shocks in boxing history.
“Your heart tells you ‘come on Tony, you can do this’. Then you meet the monster, it’s going to be like David and Goliath,” Nelson told Sky Sports.
“Usyk is a dangerous, dangerous individual. If Tony Bellew pulls this off, as far as I’m concerned, that is the biggest upset a British fighter has caused in boxing.
“This man Usyk is supposed to be the best fighter out there and I actually believe it.
“Tony Bellew has got to hope that this man is arrogant enough to underestimate him, to think he’s not good enough.”
That does seem unlikely, as Usyk dubbed Bellew the best opponent he’s ever faced in the pre-fight press conference, despite some quarters of the media interpreting it as sarcasm.
“If he [underestimates Bellew] then he might take chances and be a little lackadaisical. Then he’ll walk onto one,” Nelson added.
“I’m scared. This guy is so cool, he’s so confident, he’s so intelligent.
“I sat there and thought ‘I cannot find the chink anywhere in you’.
“You can tell when someone talks, how their hands are, how their body language is.
“This guy oozes confidence. I asked him why he chose Tony Bellew and he said ‘Because I could’.
“It’s not even arrogance. This kid just knows he’s good but now he realises that he’s brilliant.”