Steve Collins is backing Enzo Maccarinelli to beat David Haye in London on Sunday and be crowned undisputed cruiserweight champion.
Collins does not think Haye is ready for Maccarinelli
The all-British bout has been dubbed the biggest since Nigel Benn fought Chris Eubank in 1993.
And former two-weight world champion Collins, who beat both Benn and Eubank, told BBC Sport Wales: "I honestly believe Enzo is going to win."
"I'm going to see what I believe will be Enzo ending Haye as world champion."
Former WBO middleweight and super-middleweight champion Collins is perhaps the least heralded but most successful of the middleweights of the early 1990s.
I don't think Haye is good enough for Enzo Maccarinelli
The Irishman, known as the Celtic Warrior, beat Eubank to be crowned super-middleweight champion and defended the title twice against Benn.
Collins admits he is surprised Maccarinelli has not moved up to the heavyweight division, but says he could do so after the Haye fight.
"I have a personal interest in this fight because I have a lot of respect and am very fond of Enzo Maccarinelli as a person, and as a fighter, I really do think he's great," said Collins.
"I just like the fact he's got punch power. Everyone loves a banger and Enzo's a banger.
"People love to see fighters who can knock people out and Enzo can knock people out and that's what's appealing about him.
"I have often wondered why he hasn't gone up to heavyweight.
"I believe he could become a great heavyweight champion. I think he could surpass everybody. He's got the physique, he's got the size, he's got the power."
Swansea's Maccarinelli, 27, retained his WBO title in December, beating Mohamed Azzaoui in the fourth round at Cardiff's Millennium Stadium.
Londoner Haye, also 27, peeled himself off the canvas to sensationally stop France's Jean-Marc Mormeck in Paris a month earlier and claim the WBC and WBA straps.
But Collins said: "David Haye has not convinced me yet. He has been involved in one or two good fights, but he hasn't convinced me yet that he's a great champion."
"If I was David Haye's people, I would probably would have held him back a bit because I don't think he's ready for it.
"I don't think he's good enough for Enzo Maccarinelli. I could be proved totally wrong but that's my feeling right now.
"I want Enzo to win, simple as that."
*See Collins and the full big-fight build-up on Sport Wales, BBC Two Wales & 2W, on Thursday, 6 March (2200 GMT).