Danny Green claims he possesses a punch in his armoury that will knock out American superstar Roy Jones Jr "for a week" if he catches him clean in their boxing world title bout in Sydney on Wednesday.

However, punters are tipping the opposite result with challenger Jones favoured to become the first fighter to stop Green inside the distance.

Green, 36, will defend his IBO cruiserweight world title belt against 40-year-old Jones, who is bidding to become the first man in boxing history to win a world title belt in all five divisions from middleweight to heavyweight.

Jones (54-5, 40 KOs) has been stopped just twice in his 20-year career, by Antonio Tarver and Glen Johnson.

"I won't name which punch, but there's one punch, if I hit him clean with it, he is going to be knocked out for a week," Green told AAP.

"His speed can baffle me, but my power - it can hospitalise someone.

"My fists are like bricks."

Green (27-3, 24 KOs) has never been stopped, although he was floored by Argentinian Omar Gonzalez back in 2004.

Jones, who has won eight world title belts across four divisions, is a strong betting favourite with punters - with at least one placing $10,000 on the American to win by knockout.

Player has Jones a resounding $1.33 favourite, while Green is at $3.10.

Green and his trainer Angelo Hyder exuded confidence at the weigh-in, as did Jones despite a possible eve-of-fight mind-game by the champion.

Jones had to wait several minutes for Green to weigh-in after him, but remained relaxed and conducted an impromptu Q and A session with the large audience which included leading Australian heavyweights and former rugby league stars Solomon Haumono and John Hopoate.

Green told the patrons of Star City Casino he was "relaxed and in a good place".

Hyder stressed he would not have changed any aspect of Green's preparation.

"There's no excuses, (he) is either good enough or he's not," Hyder said.

The veteran trainer acknowledged Green would need to maintain constant pressure on his older opponent.

"You can't let Roy Jones fight his fight ... if you want to beat Roy Jones, you've got to go in there and take it from him."

Hyder predicted Green would outweigh Jones by up to four kilos come the fight and suggested immortality beckoned for his boxer, who is relishing his underdog status.

"The biggest reward is if he defeats Roy Jones, he will be remembered forever," Hyder said.

Jones, who is fighting professionally outside the United States for the first time, was confident he could handle any strategy Green employed.

"Whatever he does, I'm ready for it," Jones told AAP.

"If he wants to fight toe-to-toe, that's fine, if he wants to box, that's fine.

"I'm sure he doesn't want to box because it's going to be kind of stupid, that's what I do for a living."

Green's good friend and former housemate, WBA and WBC super flyweight world champion Vic Darchinyan said his former stablemate didn't necessarily need to look for a knockout.

"Everyone says, because Roy Jones is very speedy and skillful, Danny has to knock him out to win - no, Danny has to win every round," said Darchinyan who is in the US preparing for his December 12 title defence against Mexican Tomas Rojas.

Wednesday's fight will be refereed by Englishman Howard Foster.

Factfile

Danny Green
Age 36.
Height: 183cm
Weight: 81.30kg
Stance: Orthodox
Professional Record: 27-3, 24 KOs.
Year of first professional fight: 2001
Major titles won: WBC supermiddleweight, WBA light heavyweight, IBO cruiserweight

Roy Jones
Age: 40.
Height: 180cm.
Weight: 81.45kg.
Stance: Orthodox
Professional 54-5, 40 KOs.
Year of first professional fight: 1989.
Major titles won: IBF middleweight, IBF supermiddleweight, WBC, WBA, IBC, IBF, IBO light heavyweight, WBA heavyweight.