If Sunday's NRL grand final was portrayed in a Hollywood thriller, critics would pan script writers for trying to cram too many sub-plots into one 80-minute bonanza.

On the surface, St George Illawarra versus the Sydney Roosters represents a simple equation - the competition's most dominant side of the past two seasons up against a Cinderella story riding a wave of momentum.

But scratch through the exterior of the first all-Sydney decider in six years and the enormity of what is at stake is quickly revealed.

There is the 31-year premiership drought the Dragons are trying to break, a gap which extends into a history before St George's merger with the Illawarra Steelers.

Five times the Dragons have been back to the big dance since, only to fall short of securing the holy grail.

After collecting last year's wooden spoon, a tilt at the title seemed light years away for the Roosters, but they are now on the verge of becoming the first side since the 1933-34 Wests Magpies to go from last to first in 12 months.

And what about Roosters coach Brian Smith attempting to end his 27-year crusade for a first premiership win? He's reached this very stage on three occasions without success.

In two of those bids - with St George in 1992-93 - he was denied by Wayne Bennett, who is again his adversary on Sunday night.

For Bennett, this shapes as the final challenge in him being recognised as the greatest NRL coach of all-time. Can he get a franchise that has so often underachieved over the line?

Then there's the players.

Roosters prop Jason Ryles - who made his name during a nine-year stint with the Dragons - copped the brunt of criticism for the joint-venture's finals failures along with former skipper Trent Barrett.

Now Ryles looms as a major obstacle in St George Illawarra's way.

Rookie centre Kane Linnett was told he didn't have a future in the big red V, only to be given a chance by the Roosters while teammate Todd Carney didn't appear to have a future anywhere after a series of alcohol-related incidents at Canberra.

The five-eighth then completed a spectacular return to the NRL, capped by winning this year's Dally M medal.

So many dreams, so many stories - but only one winner.

"For me and a few of the blokes we've waited a long time for this," Dragons skipper Ben Hornby said.

The Dragons go into the game as favourites - and won both games between the sides this year - but the Roosters know they have the game to spring an upset.

"When we've been good and or passes have stuck and our plays have come off, we've been able to put a lot of points on teams and a lot of points in a short period of time," Smith said.

"That's the danger for them - if we happen to do that we can trouble them.

"Who knows what we're capable of this weekend - we don't, so no-one else does."

While the Roosters will bank on the unpredictable, the Dragons will rely on the defensive formula which has proved so successful since Bennett's arrival at the club last year.

It was enough for the Dragons to hold off the Roosters 19-12 in their Sydney Cricket Ground epic back in round 22.

Smith admitted after the game the performance showed just how far the Roosters needed to go to be a premiership threat, but Bennett denied the result would give the Dragons an edge going into this weekend's meeting.

"We've got confidence from two years of consistently playing well," Bennett said.

"That's where we get our confidence from, it doesn't come from one game."

Unfortunately for Bennett's Dragons or Smith's Roosters, one game is all they've got on Sunday.

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