Few tipped Central Coast to make the inaugural A-League grand final six months ago.

And after watching his unfancied Mariners beat runaway minor premiers Adelaide 1-0 in the preliminary final, even Central Coast coach Lawrie McKinna admitted he never thought it possible.

"We honestly felt before the season we'd feature in the finals, but never in the first grand final," said the Scotsman, who joked he felt like doing a few somersaults after the game.

Yet McKinna's Mariners will next Sunday vie for a place in Australian football history when they tackle big city rivals Sydney FC in the fledgling league's grand final at Aussie Stadium.

And not just happy to be there, McKinna promised the Mariners - who have now gone 12 games unbeaten - would go full tilt to claim the title.

"We've still got another 90 minutes to go so we can't get carried away," he said.

"People sometimes think you get into a grand final and that's it, but that's not what we're going to do.

"We're going to enjoy the week, we've enjoyed the ride all this season, but we'll go out there with nothing to lose.

"We said last week there was no pressure on us (for the preliminary final) and that continues this week."

The Mariners had no shortage of heroes before a crowd of 11,405 at Hindmarsh Stadium on Sunday.

Tom Pondeljak's seventh-minute strike - just his second goal of the season - put the visitors in front early before some superb goalkeeping from Danny Vukovic and desperate defence staved off a second-half Reds fightback.

The goal came with plenty of good fortune - Adelaide defender Adam van Dommele virtually tripped over while trying to clear Andre Gumprecht's low cross, allowing Pondeljak to stab home what proved the winner.

But it was deserved reward for Pondeljak, Gumprecht and the Mariners, who dominated the opening 25 minutes against a nervous Adelaide.

Vukovic made several fine saves, the most important being his diving effort to deny Adelaide skipper Ross Aloisi midway through the first half and then Shengqing Qu in the second.

He was saved by the crossbar off a Fernando Rech free kick in the final 15 minutes, and then by some desperate goalline defence by the likes of Socceroo Michael Beauchamp and Wayne O'Sullivan near the death.

But it took nothing away from the performance.

"I think we deserved the win," McKinna said.

"They threw everything at us in the second half, but we defended bravely, Vukovic made a couple of crucial saves, one or two was cleared off the line. I thought the defence was unbelievable, we really dug in today.

"It's just 90 minutes to go now, and it's the old cliche, anyone can win."

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