'Grub': Paul Gallen's choice of horse hair gloves fans pre-fight flames with Sonny Bill Williams

Sonny Bill Williams has labelled Paul Gallen a "grub" after it emerged that the Sharks great will wear horse hair gloves in their fight on Wednesday night.

Horse hair gloves are viewed by many as packing more punch than foam ones and are not permitted by all boxing bodies around the world.

But Wide World of Sports understands there is nothing in the fight contract preventing their usage and Gallen has signalled his intention to wear them.

Sonny Bill Willams vs Paul Gallen at Sydney's Qudos Bank Arena on July 16 is available to order live and exclusive on Stan Pay-Per-View for $70

"He's a grub," Williams told 9News when informed of Gallen's move before flying from the Gold Coast to Sydney on Friday.

"That's how he played the game and that's how he fights. So, I don't know, I'll talk to my team, I'll see if it's... you know, it is what it is. At the end of the day, we're going to get in that ring on Wednesday and we're going to fight.

"So horse hair, non-horse hair - it's the first I've heard of it."

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A cranky Gallen called Williams a "mutt" and a "weak-gutted dog" as tensions further escalated on Nine's State of Origin coverage this week.

Gallen immediately went on the offensive as the New Zealander struggled to get a word in.

"He's the guy that will be in a park and if a little five-year-old said something to him, he'll stand there and probably pick an argument with him, you know, until he's proven right," Williams said.

"You're never going to win with these type of guys and that was evident after the State of Origin. I think he must have went in and gave the Blues a pep talk before the game, knowing his track record with the Blues."

Gallen captained NSW to a drought-breaking series victory in 2014 but his overall Origin record was nine wins and 15 losses.

"A dog, a mutt... for me, just seeing how angry he was, pretty crazy," Williams said.

"I'm not a trash talker, but I'll talk honest truth. And he pushed me there.

"He's a drug cheat, he got caught for performance enhancing drugs, they took the ban, some other things that I've said about him are true. So when I hear him call me a dog - I just see the anger in him because someone's actually told him straight to his face and he doesn't like that, you know."

Williams was again referencing the Sharks supplements saga that rocked the NRL in 2011.

Gallen pleaded guilty in 2014 to having unknowingly used banned peptides and reportedly received a payout of $700,000 in 2020 to stop him taking legal action against the club.

"I want to give him a hiding, get it done, give him a hiding," Williams said.

"Apparently I've been running for 10, 15 years, so the running will stop next Wednesday. Honestly, I would love to knock him out.

"But I'd also like to bash him for eight rounds too."

Williams has been trained by Jai Opetaia's father, Tapu.

He has spent more than two months with him on the Gold Coast and Opetaia is predicting a knockout victory for his charge.

"It's become personal now and they're ready to punch the crap out of each other," Opetaia told 9News.

"I think it's going to be a big night. Someone's going to go to sleep I think."

Opetaia said Williams was one of the nicest and most polite people he had ever met.

"But you can tell he's reached the the pinnacle of rugby league and rugby union, and when he needs to get down and dirty, he knows how to get down and dirty," he said.

"To play the elite sport of rugby union, you need to know when to turn the switches on and off.

"So don't worry, we've got a switch there to turn on."