NSW rugby league advisor Greg Alexander expects to see Michael Morgan fill the boots of the man he claims is the “best fullback to ever play the game”.

Queensland’s State of Origin preparations took another dramatic twist on Monday afternoon with the sudden withdrawal of hamstrung fullback Billy Slater.

He joins fellow mainstays Cooper Cronk, Cameron Smith and Johnathan Thurston – all retired from representative football – on the sidelines as a new era of Origin is ushered in at the MCG.

With that in mind many are urging Queensland coach Kevin Walters to plunge 20-year-old sensation Kalyn Ponga straight into the fray on Wednesday night in a direct swap with Slater.

But, noting the gravity of the loss, Alexander believes the Maroons will go with their trusted utility at the back instead.

“It’s a bit of a shock; there were rumours about Billy’s hamstring but we hadn’t been monitoring it closely,” he told Fox Sport’s NRL 360.

“It’s a blow for Queensland to lose Billy – the best fullback to ever play the game … and a great Queenslander.

“I’m sure he would’ve been the focal point for Kevvy’s game plan but they’ve got some great options.”

He said the Blues’ plans wouldn’t change much but that, if shifted, Morgan’s running game would present them with a point of difference.

“A lot of what we have been working on surrounds Billy, but only because he’s so good at what he does,” Alexander said.

“Billy covers pretty much everything perfectly but it doesn’t mean the man coming in won’t offer his own strengths.

“And Morgan if he comes in, is powerful. He’s a great running fullback.”

Former NSW hooker Michael Ennis thinks Greg Inglis will move from the centres to replace Slater but has backed Ponga to star if called upon.

“Boy oh boy is it an opportunity (for NSW),” he told Fox Sports.

“He’s (Slater) a wonderful attacking player but it’s his defence they’ll miss most.

“It’s perfect for him (Ponga) to come in. He’s young and flamboyant and ready to take on the world.”