Matterson not expecting halves switch if Cronk out

Roosters forward Ryan Matterson is hopeful halfback Cooper Cronk will be fit to take his place in Sunday's Telstra Premiership grand final – but if not, expects young playmaker Sean O'Sullivan to get the nod as a replacement.

Matterson played three games this season in the No.6 jersey when Luke Keary was out but reckons it would be a different scenario if the club's main playmaker in Cronk was scratched and the five-eighth was asked to move to the halfback role.

However, he stressed he would aim up in whatever task coach Trent Robinson asked of him.

"Fingers crossed Coops can play, he's a big part of the team," Matterson told NRL.com.

"Whoever Robbo names we have 100% faith in them. The boys have been training all season for this. We've got a 36-man squad so I'm pretty sure whoever Robbo chooses is going to be the best candidate for the job."

O'Sullivan has had a strong season for feeder club Wyong in the Intrust Super Premiership, Matterson points out. He scored a try on NRL debut in round 18 in the only game this year Cronk missed, and has since made the 17 on the bench three more times without getting on the field.

Since Matterson's three games in the No.6 from rounds 21 to 23 he has mostly played in the middle in a sort of roving lock type role in four consecutive games off the bench.

"I haven't been prepping for the halves but football is football, you run hard and tackle hard and create opportunities," Matterson said.

"It's the same group of boys playing the same game of football really. It would have been about a month ago [the last time I ran in the halves].

"I don't prepare myself for the halves but if that opportunity comes then I'll take it."

Instead, Matterson said he had relished the chance to get his work rate up in a middle forward role.

"Since my head knock I've found myself playing in the middle now and I'm really enjoying that role, playing with Victor [Radley], playing with Zane [Tetevano], playing with Lindsay [Collins].

"We just have a middle now, the boys come on, run hard, pass well, tackle hard, communicate well. [The positional switch] just went that way.

"Robbo asked how I'm enjoying [the middle], I said I'm getting my hands on the ball more, I'm enjoying it. Especially playing with the big boys. It just happened like that."

The former Parramatta under-20s star said he is just relishing the chance to play his first grand final since his under 16s days.