COOPER Cronk has taken part in a private training session away from his teammates in a bid to play in the 2018 grand final.

Foxsports.com.au understands Cronk was testing out his busted shoulder in a series of one-on-one drills with a trainer in North Sydney.

Cronk was seen going through a range of movements and grappling with the trainer in Neutral Bay, nearby the Roosters halfback’s home.

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Round 20

It comes as Cronk took no part in the Roosters’ captain’s run on Saturday as mystery continues to surround his availability for Sunday’s decider against Melbourne.

Cronk will be given until the 11th hour to prove his fitness and has adhered to a painful and rigorous rehab program after injuring his left shoulder in the preliminary final.

Roosters supremo Nick Politis on Saturday told The Daily Telegraph he’d “never seen anyone like Cronk” as he reflected on the club’s $1.8 million investment.

“Cooper is putting in four or five hours a day with the physiotherapy people,” Politis said.

“Cooper is the sort of guy who won’t play unless he can contribute. It was fantastic what he did last week against Souths but he can’t play again with one arm.”

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The Roosters have very strongly hinted all week that Cronk won’t play, even naming him as the final reserve in an extended 23-man squad.

But some have questioned whether the tri-colours harbour serious doubts about his fitness or are playing a carefully crafted game of chicken with their star man’s former club -- even naming Mitchell Aubusson in the No.7 jersey.

Regardless Cronk has prepared himself to play through the pain; the ultimate professional has left no stone unturned in his recovery and preparation in one of the biggest weeks of his career.