Parore was influential in Tua's training regime in the lead up to his knockout victory over Shane Cameron in 2009.
"He is a gentleman who gets me in great shape."
Tua had his fight against Ustinov pushed back two-and-a-half months earlier this year after suffering a calf injury.
"The calf is holding up ... it is good for an old fella," he said. "For three weeks I thrashed the calf and it is holding up well."
Tua says his goal is to get one more crack at a world title fight but said he was not sure what would happen following this bout.
"I have to be open minded and flexible and see what happens after this fight and make a decision.
"So I will live and die on this fight."
Tua said he had family and close friends in Rotorua who had supported him during his career.
"It's a place that I hold dear to my heart, RotoVegas. I boxed there in the amateur ranks and visited there often."
He said his sister and her husband pastored a church in Rotorua and his good friend Mike Sykes was a local boxing trainer.
Tua said he was not worried about Ustinov (53-9-1) who is currently ranked eighth in the world on the IBF heavyweight standings.
"I don't think about what he does," he said. "I think it is important that I don't get sidetracked about what he does."
Tua said he was simply confident in his own abilities and fitness.
Ustinov has not fought in a pro bout since September 2012 while Tua has not fought since his loss to American Monte Barrett in August 2011.