Every shadow combination he throws comes with pointed commentary. "I'm not going anywhere," he tells the ghost of Wladimir Klitschko, the man he faces on Saturday night for the undisputed heavyweight championship of the world. "You're too slow mate, you're too slow."

Leapai, the 34-year-old feel-good story from Logan in south-east Queensland, has imagined this fight for months, if not years. Now he verbalises what he hopes to achieve in nearby Oberhausen, when he meets a man that has lost just three fights in a decade of ironclad ring domination.

He bends down, fires off some rips to the body of the apparition he faces, then rises up with a fierce left hook in the mould of Joe Frazier, a man whose fighting style he idolises and in many ways hopes to emulate against the giant Klitschko.

"Why you holding? You're a girl. Let's fight. Let's fight. Come on Klitshcko, come on, bro," Leapai mutters as various members of his entourage file in and out of the room at the most ungodly of hours.

"You're the world champion," he says, to which his loyal supporter and financial backer, Phil Murphy, loudly retorts: "Not for much longer!"

Leapai again: "Is that all you've got? Quit now Quit now."

Just days out from one of the biggest fights in the history of Australian boxing, Leapai remains calm, collected and blessed with a sense of destiny and confidence that bely his status as the biggest of underdogs. He has been a Cinderella story but few outside of his camp believe the slipper will fit against Klitschko.

The father of six has taken everything in his stride. Not long ago, he was driving a delivery truck in Brisbane. Now he's flying first class and about to attempt to become Australia's first heavyweight world champion. Nobody from Australian shores has even challenged for 106 years, when Bill Squires had a shot in 1908.

Leapai has become a creature of the night, slowly tweaking his body clock so that he will be at his peak at about 11pm local time on Saturday night. Before that, he will load up on what might be his secret weapon – sweet potato – as he gives himself a super-hit of pre-fight carbs.

He has based himself in Essen, the industrial city in Germany's north-west. It was flattened time and again in the Second World War as Allied bombers swept in to crush the Krupp ironworks and hinder the German war machine.

He's a long way from Woodridge but surrounded with those who have helped him live and shape the dream. His trainer, Noel Thornberry, spent an hour with him working the pads during the early morning session in the deserted Philharmonie Room, which presumably is more accustomed to the strains of Beethoven than the thud of leather glove on pad.

Murphy, a land developer and large investor in the NRL's Brisbane Broncos, urges him on at every point, as does Alex's father Faataui, who will be in his corner against the man ominously known as ''Dr Steelhammer''.

Also on hand is Noel's brother Ricky, a talented middleweight who went the distance with the great Welshman Joe Calzaghe in 1999, taking all manner of punishment but somehow finding his way to the finish line. Noel highly values his brother's input during fights and listens intently when he chimes in with advice.

Leapai and Klitschko will come face-to-face in Dusseldorf on Tuesday at a pre-fight news conference. Leapai said he'd rather not see his opponent until the weigh-in on Friday for fear he may run his mental race before the ring sounds.

And although he was happy to trash-talk a ghostly opponent in an empty room close to dawn, he said he would remain circumspect when he sees Klitschko, all 198 centimetres of him, in the flesh.

“I don’t want to think too hard about the fight because we are not fighting the fight now,” Leapai said. “A lot of people think about the fight all week and by the time they get in the ring, they have forgotten what they have to do.

“I just blank it all out. I will save everything for that night."

Leapai's mission isn't just to bring the WBA, IBF, WBO and IBO belts back to Australia. He might just be able to save the heavyweight division, which has suffered a lack of interest outside of Europe under the twin reigns of the Klitschko brothers Wladimir and Vitali (now retired), two clinical executioners who have demolished anyone in their path.

"I think I have the style, the old-school style that livens boxing up. The style that brings boxing back to life," Leapai said.