Challenger Mundine, 37, insists he is still at the peak of his powers despite being the betting underdog for the Sydney Entertainment Centre clash.
Mundine (44-4, 26 KOs) scaled 71.95kg at Tuesday's weigh in.
Geale (28-1, 15 KOs) making his fourth defence, scaled 72.50kg, just inside the limit of 72.57kg.
"The closer you can get to the limit the better, he's timed it pretty much to perfection," Geale's trainer Graham Shaw told AAP.
Both Geale and Shaw said Mundine looked in good shape at the weigh-in.
Mundine was in a typically confident mood as he left the weigh-in area at The Star Casino.
"I'm the best ever, the number one, the best athlete ever, you can't mess with me," Mundine declared.
Mundine was responsible for inflicting the only professional loss on Geale's record, taking a split points win in Brisbane in 2009.
Since then, Mundine has won an interim light-middleweight title and gone 8-1, losing to Garth Wood, winner of the TV reality show The Contender.
Geale, 31, has won seven straight since losing to Mundine and has accumulated plenty of big fight experience, taking world titles off Sebastian Sylvester and Felix Sturm in Germany.
"Anthony talks like he wants it, but he's sort of finishing up, he knows he's towards the end of his career," Geale told AAP.
"I'm still hungry, I'm motivated every day I still want to get better.
"I'm not at the top. I still believe I've got a lot more to improve.
"Just the improvements I've had in the last six to 12 weeks, have been awesome."
Geale stopped short of predicting a KO win, but Shaw said he wouldn't be surprised if his charge won inside the distance.
Conventional boxing wisdom has it that Geale's renowned work rate over 12 rounds will eventually wear down the older challenger in a classic battle between two quick-handed boxers.
However, Mundine was adamant the bout wouldn't come down to him trying to match the champion's output.
"There are many ways to skin a cat, that's the game plan, I can adapt, I'm very adaptable," Mundine said.
"I believe I'm at the peak of my powers, that's what I'm going to show on Wednesday.
"Because I've been through all the scenarios and I'm starting to pay attention to detail now in my art, I never used to."
American Robert Byrd will referee the bout, with three Australian scoring.
The undercard features world ranked featherweight Joel Brunker up against three-time world title contender Ivan Hernandez of Mexico.
Daniel Ammann defends his national light heavyweight title against unbeaten David Aloua and Lauryn Eagle fights Nadine Brown for the vacant national women's lightweight championship.