"Even though he's short he's got a lot of experience and titles so he's a legend of boxing and I feel privileged to have the opportunity to fight him," he says, adding it is a buzz for them both to have a chance to make it to the pinnacle of professional boxing.
He is sceptical of yesterday's revelations on the 40-year-old's calf injury scare.
"I'm not too sure how true that is or how serious it is," says the 140kg fighter who has lost only one of 29 heavyweight boxing bouts - to world IBF No 1 Kubrat Pulev.
"They might just be tactics and strategy, especially if the media is involved because nowadays they like to put things in their own words - with all due respect to you - to make a big drama out of it all," says the former soldier who has been awarded an "Order of Courage for Services to the fatherland during the Chechen campaign.
It would be a shame, Ustinov feels, if the fight is delayed because of the investment of time and cost in planning, training and travel.
Depending on the duration of any ensuing postponement, he will decide whether to stay or jet back home.
"I will be very upset if the fight doesn't take place at all."
While relishing sightseeing during trips, he can't wait for the media promotional side of things to end so he can conduct full-on training daily.
"While I'm standing here talking to you David Tua is training really hard," he says with a grin, dropping his huge frame to shadow spar to emphasise the point.
He considers himself a normal person growing up in school before attending university and playing normal sports such as ice hockey, soccer, volleyball and skiing and has numerous champions certificates at home to validate his prowess.
A kick boxer, it wasn't until he turned 25 that he took up boxing, stumbling on to it quite by chance when a coach spotted him before he went on to clinch a world championship title following 18 months of training.
"Only then I started thinking boxing could be my career and become an income."
He doesn't consider himself a hero, a superman or a champion, for that matter, as he takes baby strides to become the best fighter on the planet.
"I am respected in the community and I know there are few other sports people who value my opinion and occasionally ask me for advice."
His parents, no doubt, are very proud: "For them I'm still that little naughty boy and that'll probably never change."
The nomadic lifestyle means having a girlfriend isn't practical.
While the Kiltschko brothers are his mentors, he suspects a day will come when they'll retire as he makes a charge for the bragging rights.
"I will have a look at the opportunity to fight either of them if it arises," he says, thanking the Ukrainian siblings for putting Europe on the map.
He loves New Zealand, its people and the temperate winter climate (Belarusia is -20deg and 30-plus in summer).
"The only criticism I have of New Zealand is that it's too far away from us. With 32 hours on the plane, it's very hard for me because I have long legs that do not fit between seats."
