Alex Leapai Jnr's professional boxing career has begun with a scare, the teenage behemoth overcoming New Zealander Joe Ageli's frenetic start to win an Adelaide slugfest.

The 18-year-old son of former world heavyweight title challenger Alex Leapai lost an action-packed first round before dominating the second half of the four-round bout on Wednesday night.

Victory was decided in a more even second round.

One judge awarded it to the Kiwi 31-year-old, but the other two crucially gave Leapai the round, setting up his win 39-37, 39-37, 38-38.

Both men swung freely, Leapai taking some early punishment before delivering a retort that culminated in a powerful six-punch combination in the final seconds of the fourth round that somehow didn't floor the staggering Ageli.

The 122kg giant was a schoolboy rugby league standout signed to the Sydney Roosters and then Gold Coast in the NRL.

But he opted late last year to follow in his father's footsteps full-time.

"It was a great experience, great atmosphere and just great to get some rounds in," Leapai told AAP.

"Ageli didn't faze me; he was just throwing some wild punches. Some stuck, but I had control.

"But I'll take this and learn from it. The whole week was awesome."

Leapai is trained by Noel Thornberry, who took Leapai's father all the way to a four-belt world title shot with Ukraine giant Wladimir Klitschko 10 years ago in Germany.

"I'll be back training next week and I'll fight every month if I can, but I trust Noel to make the call on what's next," Leapai Jnr said.

Headliner Jackson England then won a split points decision - 96-94, 96-94, 93-97 - against former world champion Jamel Herring that will likely see the Australian super featherweight move inside the top-10 of the WBO rankings.

A host of retired AFL players filled the nine-fight card that served as a prelude to the city's Gather Round.

Former Brisbane and Carlton star Mitch Robinson was an impressive debut winner against former Richmond talent Kayne Pettifer, who suffered his first loss in a four-fight professional career.