The fight will take place at Madison Square Garden on Saturday night
Roy Jones Jr believes Joe Calzaghe underestimated Bernard Hopkins but expects the Welshman to bring his "A game" when the two meet on Saturday.
Jones added that he expected Calzaghe to be his biggest obstacle since James Toney, who Jones beat to claim the IBF super-middleweight crown in 1994.
"Calzaghe didn't expect much trouble from Bernard - he said he had to train harder for me," Jones told BBC Sport.
"Calzaghe wasn't on top of his game for Bernard, but he will be for me."
The inside track on Roy Jones Jr
Newbridge southpaw Calzaghe, 36, defeated Hopkins on a split decision in Las Vegas in April, although his American opponent gave him plenty of problems.
Calzaghe has since claimed that he has been more focused ahead of his New York fight with Jones, although the Florida native says he is not worried by the inevitable Calzaghe onslaught.
"The timing of the fight and the calibre of fighter he is, this is probably the toughest since James Toney," said the 39-year-old Jones, who meets Calzaghe at Madison Square Garden for the de facto light-heavyweight title.
"James was the best skilled fighter I ever fought.
"But it won't be a case of whether I'm going to be able to match his punch output.
"In pro boxing, 10 pitter-pats are about the equivalent of one big punch. He threw twice as many punches as Bernard but they were pitter-pats.
"But he only got the credit for about half those punches, that's why he only won on a split decision. In pro boxing, I don't have to match his output - just be more accurate."
Jones, a four-weight world champion, is thought by many to be the finest fighter of the last two decades.
However, since becoming the first former middleweight world champion to claim a heavyweight world title in 106 years when he beat WBA champion John Ruiz in 2003, he has fallen from grace.
After moving back down to light-heavyweight, he was knocked out in consecutive fights by Antonio Tarver and Glen Johnson before losing a rubber match to Tarver on points.
Jones has since gone three fights undefeated, although the general feeling is that his best days are well behind him.
If you've got an undefeated fighter who's making tons of money for you in your country, you're going to keep him at home and keep him undefeated
Roy Jones Jr on Calzaghe
Many observers feel that his fight against Calzaghe has come at least five years too late, but Jones maintains Calzaghe's camp, if anyone, is to blame for the delay.
"If you've got an undefeated fighter who's making tons of money for you in your country, you think you're going to take a chance on him getting beat?" said Jones, who has 52 wins from 56 fights.
"You're going to keep him at home and keep him undefeated because you make more money that way. That's just smart business. Why would he take a stupid chance like that?
"Look at Kelly Pavlik [the WBC and WBO middleweight champion], he can never demand the same kind of money again in his career because he got whupped by Bernard Hopkins [last month].
"But if he'd have had a few more fights and built himself up a bit more, he could have demanded twice the money against a fighter like Hopkins.
"But they didn't, and you won't make good money with Kelly Pavlik no more. And that's what Calzaghe's people didn't want to do, that's just the business of the game."
Jones added that he would not be seeking a rematch with Hopkins, who he beat for the vacant IBF middleweight title in 1993, if he upsets the odds and defeats Calzaghe.
Jones said: "Bernard Hopkins has constantly been talking about fighting me for the last five years and nothing's been done about it, but it's not my fault, he doesn't want to fight me.
"Where was Hopkins when I was 25 and I had my game stepped up? Fighting nobodies and he couldn't draw flies to a poo-poo cake.
"So I don't have time to waste on Bernard Hopkins. I already beat him, so what do I want to fight him again for?"
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