He may be over 30kg lighter and play in a different part of the field but Billy Slater holds the key to stopping rampaging NSW prop Andrew Fifita in State of Origin II.

That's the view of Queensland great Billy Moore as the Maroons desperately try to stop Fifita and prevent NSW from getting their hands on the Origin shield at ANZ Stadium on Wednesday night.

The Maroons have made seven changes after being blown off the park in game one with Slater arguably their biggest in after being overlooked for the series opener.

The Melbourne champion and former jockey is regarded as having changed the way fullbacks play and as perhaps the most damaging ball-running No.1 in the history of the game.


However Moore says it's in defence, in particular tightening up Queensland's middle of the field, in which Slaters' presence will be felt most.

"What I love about him is he'll bring energy to the defence, especially in the middle third where I think we got caught out," Moore told NRL360.

"He'll be in there talking, yapping, he'll do a lot of thinking for our defence, especially the young blokes. When they make a tackle and they get up a little disorientated, he'll be saying 'go left, go right'."

So what does Slater, who stands at the back and weights 89kg, have to do with halting the momentum of Fifita, a middle forward who tips the scales at 120kg?

Moore argues that no one is better than Slater at bringing energy to a defensive unit and that was the only way to get under Fifita's skin.

He called for Kevin Walters' Maroons to employ an up-and-in defence, pressure Fifita with line speed and cut off his opportunities from the inside.

"That's where I'm hoping Slater will bring the energy to lift them at that point," Moore said.

"It takes greatness to realise what your opposition is doing. When you have to lift a gear and that's what Slater and co. can do, bring us up that gear to repel the Fifita's.

"If the ball is in their court and they're dominating, we have to lift. We didn't lift in game one."