Storm coach Craig Bellamy early on Thursday said Slater was a 50-50 proposition to take on the Knights due to a hamstring issue but the veteran fullback was officially ruled out later in the day.

However Storm football manager Frank Ponissi said Slater would be a certainty to play in Origin game two in Sydney.

"The club medical staff said he was close to playing but didn't want to risk any possible season-ending injury. But he'll be definitely right to play in Origin," Ponissi told AAP.

Slater, 34, was a late withdrawal when NSW claimed a series-opening victory on June 6 and also sat out Melbourne's win over Brisbane four days later.

He looked to be running freely on Thursday at Storm training and appeared set to play in a game billed as a fullback showdown between himself and 20-year-old Knights sensation Kalyn Ponga.

Ponga has won growing support to make his Maroons debut during a sensational start to his first full season with the Knights following his move from North Queensland.

However Bellamy played down the individual clash between the pair before Slater was ruled out.

"I know there has been some talk about those two playing for the Origin spot," he told reporters.

"I'm not quite sure if that would be the case - you'd have to ask (Queensland coach Kevin Walters) about that.

"But that won't come into our consideration at all and I don't think it's going to come into Billy's consideration either."

Bellamy claimed Slater was close to playing in the Origin opener as well as the loss to the Broncos.

"He just hasn't been comfortable before those last couple of games for him to think he's been 100 per cent and the medical staff have obviously been on the conservative side, which you need to be," he said.

Walters will name his team on Monday for the second Origin match.

Bellamy is inching closer to deciding whether to accept a new $5 million contract with the Storm or move to Brisbane to replace Wayne Bennett at the Broncos from 2019.

"As I keep saying, we're getting closer but how close that is I'm not quite sure yet," he said.

"There's a few things to be thought about yet, a few things to be checked out.

"At the end of the day, as I said, I wasn't going to rush a decision to please anyone.

"Both clubs have been very patient which I really appreciate but they are probably going to just have to be a little bit more patient for a bit longer."

The fifth-placed Storm will welcome back centres Will Chambers and Curtis Scott from suspension against the 11th-ranked Knights.

Australian Associated Press