A long-time Storm assistant before leaving after last year's decider, O'Brien will return to Melbourne in charge of the competition's No.1 ranked Sydney Roosters attack in Friday night's grand final rematch.

Back working closely with Cooper Cronk after making the decision to move to Sydney, O'Brien is considered one of the best up-and-coming coaches in the game.

"He's with us now and confident we can do a good job on them," Roosters fullback James Tedesco said.

"He's really smart and gives us a lot of confidence and leaves a lot up to us and what we like.

"He'll mix different things in with set plays and gives (Luke) Keary and Cooper a lot of responsibility and if they like something then they can go for it."

O'Brien is one of several coaches to have developed under Craig Bellamy in Melbourne, including Michael Maguire, Anthony Seibold, Brad Arthur and Stephen Kearney.

But Bellamy is well aware of just how much of an asset he can be to the Tri-colours in more ways than one on Friday night.

"It's his first year there and I'm sure he's told them a few things we do here I imagine," Bellamy said.

"But at the end of the day we're not going to go and change everything we do because they might know a little bit more than this year than they did last year.

"We know what we want to do well. We know what works for us and we just need to do it really well.

"To get the Roosters you need to be playing really well and be sticking to what works for you."

Meanwhile Roosters coach Trent Robinson doesn't expect Cooper Cronk to be overawed in his first trip back to AAMI Park since departing at the end of 2017.

Cronk played the Storm twice last year, but those matches were in Adelaide and Sydney.

"I know Cooper pretty well now. I would say he would have put it in the right place," Robinson said.

"He would be excited about coming back here to play, it was his home for a long time."

Australian Associated Press