Central Coast Mariners midfielder Rostyn Griffiths hopes a year-long build-up culminates in his team taking the biggest prize of all - the A-League Grand Final.

The Gosford club have been one of the surprise packets this season, performing brilliantly throughout the regular season to finish in the shadows of league leaders Brisbane Roar.

But now they have made their way through to the playoff against the Roar and Griffiths is looking for a fairytale finish to an already successful campaign after being tipped to finish way down the table.

"In terms of actually building towards it, it has been the whole season as well, we can't forget that, we have been looking forward to it all season," Griffiths said.

"It's the biggest game in the A-League and probably in the history of the A-League in my opinion, so a massive game and I'm just looking forward to it.

"People wrote us off. I read a few magazines which all said we would finish eighth or ninth, and a few of the boys have sort of kept that, but from day one of Arnie (coach Graham Arnold) coming in we had belief. We had a system and a structure, and added a couple of players this season around the players that we already had and built a solid team."

As for the match itself, the former Blackburn Rovers man says that his side are most certainly the underdogs.

"The pressure is all on them, and has been on them all season since they have had their good run," he added.

"We have been the underdogs every time we have played against them this season and that's a title we're happy to have, and I am happy to have as well because the expectation is not on us, we have proven a few people wrong this season, especially in the last game we played against them, and hopefully we can prove a few people wrong again."