Finding someone willing to spar with Alex Leapai Jnr is proving tricky for trainer Noel Thornberry.
"Nobody wants to go near him; they all tell me, 'no way I'm putting my guy in with Alex, he's a f***ing monster'," the long-time boxing servant told AAP.
The 18-year-old son of former heavyweight world title challenger Alex Snr, Leapai will make his professional boxing debut in Adelaide on April 3 against Joe Ageli (2-1).
Leapai and Ageli will face off at the official press conference on Thursday.
At 195cm and around 120kg, he was hot property in NRL circles as he completed school in Logan, playing footy and hitting the pads with his father at Thornberry's Gatton gym.
Originally signed to the Sydney Roosters, Leapai moved closer to home with the Titans before opting to instead pursue a full-time boxing career earlier this year.
That greatly pleased Thornberry, who was in his father's corner when he fought Wladimir Klitschko in Germany for the world title 10 years ago and is adamant his son is a world champion in the making.
His biggest issue now is locking down a sparring partner, with only Joe Goodall so far game enough to do some rounds with the teenage prodigy.
"Even if I tell them Alex will tone it down and go easier, nobody is game," Thornberry said.
"Guys - experienced, fully-grown men - that have sparred (with) him previously come out saying they were just trying to survive.
"Joe's been his only sparring (partner), but I'll make sure he gets more; whether he has to fly to New Zealand or we bring someone to him.
"It's very exciting. I don't know of any other boxer his age who is more imposing on the planet."
Thornberry wants to get Leapai back in the ring for a second fight within months of his debut, which will come on an Adelaide card headlined by the trainer's nephew Jackson England taking place at the beginning of the AFL's Gather Round.
Super featherweight England in December narrowly lost to Liam Wilson, who will fight Oscar Valdez for his WBO world title in Phoenix next month.
Former AFL players Kane Kornes, Nathan Brown, Dale Thomas, Dane Swan, Anthony Rocca, Corey McKernan, Mitch Robinson and Kane Pettifer will all fight on the card.