By Melissa Woods

Veteran boxer Danny Green admits he lacks match fitness compared to his Argentine opponent Roberto Bolonti as he heads into his first fight in almost three years.

The 42-year-old four-time world champion is taking on "The Beast" Bolonti at Melbourne's Hisense Arena on Wednesday night.

Green's last fight was at the same venue when he out-pointed Kiwi Shane Cameron to regain his IBO cruiserweight world title.

While he never officially retired, he hasn't punched in anger since while Bolonti has been busy.

In the same time the 36-year-old Argentine has fought eight times, only losing once to Juergen Braehmar for the WBA light heavyweight world title but going the distance with the powerful German.

"It's a big challenge because he's just come off a win," Green told AAP.

"He's been fighting regularly at a high level in the last two and half years so he's got an edge there because he's got match fitness."

Bolonti was called in last week to replace injured Green's original opponent Slovakian Tamas Kovacs, who injured his neck.

Due to the short notice, Green's camp had to find someone ready to go and Bolonti fought just over two weeks ago, barely raising a sweat in his two round TKO job on Venezuelan Williams Ocando.

Despite the lack of fights, Green said he kept training the whole time and didn't feel he'd lost his touch.

He said he'd been studying Bolonti's fights against Braehmar and also top British light heavyweight Tony Bellew to see how he performed on the big stage.

Green said he'd had previous success against Argentinians and knew what to expect, talking of his 2004 fight against Omar Gonzalez and in 2009 when he flattened Julio Cesar Dominguez.

The West Australian suffered the first knockdown of his professional career in the second round against Gonzalez before the fight was stopped in the fifth because of his opponent's cut eye.

"The first person to put me on my backside wasn't my brother it was an Argentinian in 2004," Green said.

"I won the cruiserweight title in 2009 in Mississippi against Julio Cesar Dominguez, who broke my ribs in the first round.

"I know about how tough and wild Argentinians are because I've been in a few hard battles with them."