Call it the Samoan sidestep, the Fiji handshake, a bump-off, a fend, a big "don't argue" or whatever else you want, just know it's rugby league's equivalent of a "slam dunk" and there's nothing else like it.

Tries will get plenty of cheers when Penrith meet Parramatta on Sunday in the NRL grand final. So will fine passes and clever kicks, and there will be a mighty roar when the final siren sounds, regardless of who hoists the premiership trophy.

But there won't be anything so primal, so forceful and guttural and mighty as the sound that erupts in the moment when a ball-carrier and defender collide at full speed and the man with the footy comes out on top and leaves the defender splayed on the ground, wondering what the hell just happened. 

"It really hypes everyone on," Panthers winger Brian To'o said. "That's the mad thing about it." 

Not many people do it as well as Penrith's To'o, as he showed with his beauty on Cody Walker in Penrith's preliminary final victory last week.

To'o didn't just break Walker's tackle as part of his 80-metre intercept try, he bounced Walker out of his way with enough force to send the Rabbitohs five-eighth pin-balling into other cover defenders, scattering them like bowling pins.

The Panthers powerhouse can't quite put into words how it feels or how he does it. It's just something that happens.

"It comes naturally – humbly speaking. You just have to get your body in front of them and hope for the best," To'o said.

"That's what I do, especially with the big boys I run at. Shout out to all the small boys running at the big boys.

"I just closed my eyes, then there was nobody there so I kept running until I put it down.

"I was so tired. When I caught the ball I was blowing after 10 seconds, 10 steps in and I was blowing, so all I was thinking about was getting close to the line so the boys can, I don't know, do something.

"I'm really grateful. Seriously, I'm really grateful, [because] I never thought I was going to make it."

Few players in the NRL are as hard to handle one-on-one as To'o, as many a Panthers and New South Wales opponent have found out in recent years.

The 24-year old's signature move comes when he crouches low and explodes upwards, using the power in his legs to send defenders reeling. 

Parramatta's Maika Sivo does it a different way. He's taller than To'o, so if the tackler goes for his legs he can drop down on them like a Fijian dive bomber.

Or he can get the fend out and pump into his opponent's chest like a shotgun. Sivo doesn't really plan for it much. He just gets it done.

"If they are in the way, I have no other choice," Sivo said.

"My job is to score tries. I do whatever it takes to get over the line. I just back myself and go."

To'o and Sivo won't go head-to-head in the decider, which robs fans of the chance of finding out what happens when two unstoppable forces collide on the game's biggest stage.

Taylan May's hamstring injury will mean To'o sticks to the left side, to make Charlie Staines more comfortable on the right wing, while Sivo will make his grand final debut in his customary spot on Parramatta's left.

But both men are sure to have their moments and Parramatta fans are certain to ring out the "Sivo" chant should their man uncork one of his specials on Staines.