Two in-form five-eighths have taken a back seat in the lead-up to the Telstra Premiership grand final on Sunday with all eyes on Cooper Cronk's availability against his old club in the 2018 decider.

But while the fitness uncertainty around Cronk has dominated the headlines, the battle between Cameron Munster and Luke Keary looms as match-deciding.

Both playmakers are expected to take on extra responsibility for their respective sides in Sunday's big dance regardless of Cronk's playing status.

Munster has been the cog to Melbourne's halves over the course of the season, as Craig Bellamy tinkered throughout the season before settling on Brodie Croft as his first-choice halfback for the finals.

Munster's ability to run at the line has been the cornerstone to his game since his days as the Storm's fullback in 2016, attributes that have led to another solid 99.4 running metre average in 2018.

Munster has backed up that effort with 82 tackle breaks, nine line breaks and 15 try assists.

What statistics don't show is his leadership on the paddock.

His match-up with Keary, who played a leadership role when Cronk battled through his shoulder injury in the second half against South Sydney, will be a critical one.

The Roosters No.6 has shown he has the brains to match an off-the-cusp style of play he's often used to playing outside a more dominant halfback throughout his career.

For Munster, that's a development in his game he's discovered this season.

Both players are genuine larrikins and easy-going characters. They've both won a title in the past and are at the forefront of generation next. But their game management on Sunday will be tested.

Keary told NRL.com this week he gets caught up watching vision of Munster's game as not only a player but a rugby league fan, envious of the talent his opposite number possesses.

"He's a great player and has had a fantastic year," Keary said.

"I love watching him play and the way he goes about his footy. It's good to test yourself against those types of players, especially the rep players.

"He's on the other side of the field but we'll probably see each other through the night."

Keary's numbers in 2018 shouldn't go unrecognised. He's enjoyed a stellar season outside Cronk to total 20 try assists, 13 line break assists and seven forced drop-outs.

That all goes out the window though on Sunday with one final job at hand.