All Blacks legend Sir John Kirwan has urged Kalyn Ponga not to sign a new contract with Newcastle if he wants to play for New Zealand at the 2023 Rugby World Cup.

The NRL star has reportedly been offered a four-year, $4.5 million contract upgrade, which includes an option for him to leave in 2023 to fulfil his dream of playing rugby union for the All Blacks.

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Newcastle are eager to lock down the 21-year-old, who comes off contract at the end of next year and becomes a free agent to NRL clubs on November 1. Kirwan says the Knights fullback will require at least two years in union and would be taking a huge risk by switching codes just a year out from the tournament in France.

“I don’t think he could do it in one year,” Kirwan, who made the switch from rugby league to union in 1994 when he signed for the Warriors, told the Sydney Morning Herald.

“It would be high risk on his part. He could take that risk if he wants, but this All Blacks team has some guys who are pretty big competitors and like to succeed. I think he needs two years.

“He’s got nothing to lose. A two-year contract and if it doesn’t work out he can go back to league.”

Kirwan, who scored 35 tries in 63 Tests for New Zealand, says Ponga is looking for a different challenge.

“This has nothing to do with money. For guys at this level, what I’ve realised is that they want a different challenge,” he said.

“I believe that’s what Kalyn wants, and if he wants to have a crack then it won’t be about money.”

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Ponga has spoken about his desire to play for the All Blacks, having grown up playing rugby in his junior days.

But Newcastle boss Philip Gardner — who said last month the club is a “desperate suitor” to secure the young gun’s signature — insists there would be no rugby clause in any contract that would allow Ponga to leave the NRL to play the sport.

“If any player decided they wanted to go and play a different code than us it becomes problematic for us,” Gardner said.

“It’s an interesting thing. You remember Sonny Bill Williams getting on a plane to go (to France to play rugby).

“We have to do as a club for all our players is make sure they are happy playing here for us.”

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Regardless, Gardner senses other NRL clubs could be a bigger threat at luring Ponga away from Newcastle, where he has played 40 games since arriving in 2018.

“When you look at the big clubs with the money who can splash out, certainly the Broncos would be a club,” Gardner said.

“I think they’re a bigger threat, rather than the All Blacks.

“This All Blacks thing might be real, it might not be real. I don’t know.

“I think KP will take less money to stay here, I think he is happy here and the family are happy here.”

GREEN CAUGHT OUT BY HOLMES HYPE

North Queensland coach Paul Green admits he underestimated the magnitude of Valentine Holmes’ arrival at the club.

But he said the star fullback’s breezy return to the NRL gave him confidence ahead of the side’s blockbuster season opener against Brisbane next Friday.

Former Cronulla star Holmes missed a season of rugby league while he chased an NFL contract but, after nearly a year in New York, has slotted in nicely in Townsville.

The addition of Holmes and the excitement of a new stadium has the city buzzing, but Green said his new recruit had been all business.

“I probably underestimated the impact Val has had since he’s come back,” Green said.

“The interest has been enormous and that’s only good for us and he’s handled it very professionally.

“He’s kept his feet on ground and head down. He’s a real pro and I think that’s one of the things he’s certainly brought back from the NFL.”

Holmes is all but certain to start at fullback in the first round but Green is yet to publicly anoint his No. 6.

Jake Clifford and Scott Drinkwater are locked in battle to partner halfback Michael Morgan, with Drinkwater seemingly in the box seat.

“His confidence, not that he lacked confidence … if you know Drinky that’s one thing he doesn’t lack,” Green said of the former Melbourne utility.

“But he’s taken that into his game; we saw it at the nines, he took those games by the scruff of the neck.”