The 34-year-old father of six from Logan, west of Brisbane, will travel to Germany for the April 26 bout against a man that has dominated the global heavyweight scene for a decade.

Leapai has already been installed as a $13 longshot by corporate bookmaker Sportsbet but he'll already be a winner once the deal has been signed off, with a million-dollar plus payday - at least - now heading his way.

It's a stunning windfall for a man that spends his life outside of the ring driving a delivery van, has fought his way up through pubs and clubs, spent time in jail and earned his title shot with an upset of Denis Boystov in Germany in November.

Given the status of the belt, the fight is being billed as one of the most momentous bouts in the history of Australian boxing. Leapai, who is deeply proud of his Samoan heritage, will be the first Australian to ever contest the title.

A victory would be a Cinderella story and a half but the task remains momentous. Klitschko hasn't lost since 2004, will retire as one of the most-decorated heavyweights in history and will have a mass of support on European soil.

Global boxing blogs have already given Leapai no chance against the 198cm-tall, technically brilliant Ukrainian, who has struggled to find quality opponents in the division.

But Leapai never dies wondering and will no doubt try to find a way through the Klitschko jab in the early rounds and see if he can find the mark with a looping overhand right, which has become his signature punch.

The Klitschko camp agreed to terms to avoid a January 19 purse bid. More details of the fight will be revealed in coming days.