Gallen is less than two weeks out from a heavyweight bout against former mixed martial arts sensation Mark Hunt, who made a living off famous walk-off knockouts.

The former rugby league star was in Brisbane on Thursday for a sparring session with Alex Leapai, who fought Wladimir Klitschko for the heavyweight championship of the world, and Herman Ene-Purcell, with Gallen determined to find a way to counter Hunt's lethal hands.

Gallen and Hunt's bout is the co-main event on a show headlined by the face of Australian boxing in Tim Tszyu, who faces Kiwi Bowyn Morgan at Western Sydney Stadium on December 16.

Gallen is unbeaten in 10 boxing bouts (9-0-1) while Hunt's last UFC bout was two years ago. Yet the latter is the bookmaker's favourite against a man he cheekily labelled "a full-time grub".

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"It's not the first time I've been called it, is it? I'm sure plenty of you blokes up here agree," Gallen said.

"I don't care what anyone thinks of me, man. I've got a great family and a great bunch of friends, they know who I am, they know what I'm about. People have an opinion on me and I'm not too worried about it at all."

Gallen landed in Brisbane on Thursday morning, went straight to a Slacks Creek boxing gym, warmed up, sparred with Leapai and Ene-Purcell, showered, and took off back to Sydney.

It is a necessary evil as the former NRL premiership-winning captain hunts looks outside the box in search of sparring partners.

A raft of fighters he would usually train with in Sydney's west feel a sense of allegiance to Hunt, such is the influence of one of the trans-Tasman region's most storied fighters.

"It's been a hectic day. I actually said to a couple of Alex's cousins, they're Josh Papalii's cousins, I said 'ask Papalii how hard it was flying on game day for the NRL players this year'," Gallen said.

"I felt a bit flat, to be honest, coming up here and sparring. I can't imagine what it would be like flying on game day and playing 80 minutes. I reckon that was a pretty big factor in the season this year for a lot of the NRL boys.

"I got some good rounds in, they're big boys obviously, Alex and Herman. I've got on really well with Herman for years after I fought him a couple of times, and I've been a big fan of Alex Leapai for many years.

"He was ultra-nice too before when we were warming up. He was too nice, I was thinking 'he's going to knock me out here', he was giving me a lot of tips and helping me out, giving me some things to try to do.

"I really appreciate his time, and the things he told me I will take into the fight. He even told me a couple of things after the spar. He was outstanding for me."