Paul Gallen claims Lucas Browne has cocked up his training and is undercooked for their fight

Rugby league legend Paul Gallen says Lucas Browne is "sh---ing himself" ahead of their heavyweight duel, accusing his opponent of cramming his training in a last-ditch attempt to be ready for the fight.

Gallen took aim at the fact the former heavyweight world champion had sparred six days in a row, saying "anyone who knows anything about boxing or fitness knows you can't rush it".

The Sharks legend boldly declared he'd had "10 times the quality of sparring" as Browne ahead of next Wednesday's WIN Stadium clash, confident that he's built a significant edge.

"I think he said he's sparred six days in a row. He's sh---ing himself now because he hasn't done the work earlier on. That's the fact. He hasn't done the work early on and he's trying to rush it all in now," Gallen said.

"Anyone who knows anything about boxing or fitness knows you can't rush it in a couple of weeks; you've got to build it over time. He hasn't done the work early enough and I'm going to show that next Wednesday night."

Gallen said he heard that Browne had pulled out of the sparring session he had planned to have with heavyweight boxer Faiga 'Django' Opelu in Brisbane this week.

And when prompted why he thought that may have been the case, Gallen reignited his attack on Browne's preparation.

"If he's sparred six days in a row I'd say he'd be pretty tired," Gallen laughed.

"As I said, you can't spar six days in a row. It's not good for your head, it's not good for your body. You've got to put the work in early. That's running, doing whatever you have to do fitness-wise and spar. You've got to get those sessions in and you can't rush it all in six days."