Chaz Mostert has run down Supercars rival Cam Waters in a sensational showdown, the Mustang driver completing back-to-back wins in Sydney.

The Walkinshaw Andretti United star hunted his Tickford rival for most of Sunday's 51-lap race, before overtaking with 11 laps to go to complete his weekend haul at Sydney Motorsport Park.

Claiming an early ascendancy, after overtaking polesitter Will Davison in the opening lap, Mostert gave up ground when he made his first pit stop.

He would have easily reclaimed the lead had Tickford not ordered a late change in strategy.

With Waters gunning to pull off a one-pit race, Mostert was made to hunt down his rival - and that he did.

"The last 10 laps were hell for me," Mostert said.

"When you're leading and you got a little bit of a gap, you think something's going to go wrong.

"It took me all the way back to go-kart days when I was seven or eight and you're winning a state title and you hear the engine note change."

In the end, the 32-year-old enjoyed a healthy 7.364-second buffer against Waters for his 24th career win and his third of the season.

"I was getting told the gaps to Chaz and I knew pretty quickly that I wasn't really racing him. I was racing Will and the guys behind," Waters said.

"Today was just about consolidating and getting a podium and a bag of points."

Tickford team boss Rod Nash added: "I think we scammed you a bit though. He was thinking he was coming in for a two-stopper."

Leapfrogging Triple Eight's Broc Feeney, Mostert now sits second in the standings with 105 points the difference between him and leader Will Brown.

Brown, who also opted for one pit stop, finished third for his best result since a horror outing in Townsville.

Asked if he was nervous about his claim on a maiden title, Brown said: "everyone says 'I don't look at it', but it's hard not to look at it.

"I think you've just got to be in it when it comes to Sandown and Bathurst ... It's still very open going into the back half of the year.

"When I saw Chaz coming, I put my blinker on and thought 'Do I right hook him and just put him in? I think I better not'."

Dick Johnson Racing's Davison was nowhere near the top three after claiming pole for the race, finishing sixth.

RACE 16 RESULTS:

1. Chaz Mostert (Walkinshaw Andretti United)

2. Cam Waters (Tickford Racing)

3. Will Brown (Triple Eight Race Engineering)

4. Matt Payne (Grove Racing)

5. Anton De Pasquale (Dick Johnson Racing)

CHAMPIONSHIP STANDINGS:

1. Will Brown - 1746 pts

2. Chaz Mostert - 1641 pts

3. Broc Feeney - 1593 pts

4. Cam Waters - 1360 pts

5. Matt Payne - 1323 pts