Roosters co-captain Boyd Cordner has revealed star halfback Cooper Cronk played the grand final with a broken scapula.

Cronk, who was the subject of constant speculation during the week about whether he would play after injuring his shoulder in last weekend's win over South Sydney, played all but the last few minutes of the grand final win over Melbourne.

"It will come out a bit later that Cooper actually broke his scapula and that will go down in history," Cordner told Channel Nine.

"Just having Cooper there . . . him at 30 percent we want him on the field.

"We knew Coops was touch and go and he pulled through. He was touch and go all the way up until game time and we had to make up a game plan where we protected him as much as possible and we executed that."

Wearing the unfamiliar jersey No.23, he had just 18 touches of the ball and did not make any runs and surprisingly was asked to make just nine tackles by Melbourne's attackers. And he made them all.

Cronk offered his team plenty in terms of organisation and chat and looked physically and emotionally spent when he was assisted from the field in the dying minutes.

When he spoke to Channel Nine after the match, Cronk said he would not go into detail about the injury.

"Everyone at this football club has sacrificed something for me to be here. I don't take that responsibility lightly, that was the motivation, and it was my duty to do whatever I could do to repay that faith," Cronk said.

"From the top down, everyone in this organisation sacrificed something for me to be here. I don't take that responsibility lightly, that was the motivation.

"We didn't know if I would be able to play. It was only a last-minute thing ... the boys trained all week without me playing and the whole idea was to use me as a decoy.

"Luke Keary was outstanding tonight, everything was set up for him to have the game of his life and he delivered."

Cronk said all the contact in tackles was painful, none more so than his front on shot on giant Storm forward Nelson Asofa-Solomona in the 53rd minute.

"I have never made a dominant tackle in my career, so I shut my eyes and [went] for the best [in the Asofa-Solomna tackle]."

Cronk said playing again his former team Melbourne was one of the subplots of the grand final.

"I've got this moment, I probably have to thank Melbourne Storm for everything they've done for me... It's hard for me to put into words what tonight was," he said.

"On one side is a club that provided me with everything aimed at today, the Melbourne Storm, and the other club, the Roosters provided me with a chance to start a family and play the game I love."

Young lock Victor Radley was glowing in his praise of Cronk.

"Cooper is a beast," Radley told Channel Nine. "I don't think anybody would know how bad his injury really was."

Roosters fullback James Tedesco said they only found out on Saturday at the captain's run that Cronk would play.