Defending V8 Supercars champion Jamie Whincup is in no doubt the fight for this year’s title will come down to the season finale in Sydney.

He’s just not entirely certain he’ll still be in contention come December.

The Holden star holds a narrow 15-point advantage on the overall standings ahead of this weekend’s round at Sydney Motorsport Park, the first of two in the harbour city.

Having overtaken Ford rival Mark Winterbottom in Ipswich earlier this month, it is the first time Whincup, chasing a record sixth crown, has led the championship since February.

“We weren’t competitive; we’ve only now become competitive,” the Red Bull Racing driver told AAP.

“But we’ve just got to keep doing what we do to make sure we’re still there and competitive at the end of the year when the championship’s up for grabs.”

Whincup had to wait until the last round of 2013 at Sydney Olympic Park to clinch championship No.5, having spent most of the season fending off teammate Craig Lowndes, Winterbottom and fellow Ford pilot Will Davison.

And he’s expecting nothing different in 2014.

“The championship’s as tight as it’s ever been and I’ve got no doubt it’ll come down to Homebush,” he said.

“Hopefully I’m in with a shot.”

Despite their fierce rivalry, Whincup said he had “nothing but respect” for Winterbottom, who led the championship for more than three months with four wins.

Ford Performance Racing’s leading pilot, however, hasn’t finished inside the top seven in any of the past six races.

“They were 200 points up the road at one stage and you don’t get there from doing bad things. They’ve done a bloody good job,” he said.

“They’ll be there at the end, like they have been the last three or four years, and they’re going to be hard to beat.

“We’ve got to be on our A-game. So there’s no cockiness at all, from my end.”

Unlike most championship rounds, this weekend’s event will see all practice, qualifying and racing action packed into two days.

It all begins on Saturday, when Whincup expects things to get “hectic”.

“It’s going to be a serious challenge,” he said.

“I think the key’s going to be about being on the right tyre at the right time.”