After a topsy-turvy start to the season, a “refreshed” Whincup was at his clinical best in the Top End, spruiking the benefits of a recent five-week break in the season.

Whincup wasted little time in ramping up his championship defence in his Holden Commodore. First he topped the timesheets during the two qualifying sessions, then proceeded to dominate both 35-lap, 100-kilometre races from start to finish.

“We’re only halfway through the year, the start hasn’t been as good as what we would have liked, but we’re definitely getting much better,” a happy Whincup said.

Evergreen Craig Lowndes, Whincup's teammate, came away with positive results too on his 40th birthday - two second places. Volvo driver Scott McLaughlin (4,5) and Holden trio Garth Tander (5,4), Fabian Coulthard (9,3) and Shane van Gisbergen (3,7) also netted valuable points.

Ford’s Mark Winterbottom had mixed fortunes with 6-6 results but consolidated his championship lead.

Whincup had not won a race since March and his Darwin quinella sounded an ominous warning to rivals as he defends his championship and chases a record sixth title. The 31-year-old is still fourth in the standings but has moved to within 165 points of long-time rival Winterbottom.

Saturday's results left other drivers pondering an all-too-familiar dilemma: how to beat an in-form Whincup?

“He’s always going to be dangerous and he and [new engineer] Dave Cauchi have been working hard to really create a connection,” Lowndes said.

“He’s very determined and very focussed on what he wants and what he needs."

The scene is set for a thrilling showdown in Sunday’s 200-kilometre race, worth a valuable 150 points to the victor.

Whincup was typically measured about the prospect of moving higher in the championship standings, but agreed his fortunes had improved markedly compared with five weeks ago.

“I won’t go making any big statements, but it’s certainly refreshing,” he said.

“The question is whether we can continue this for the rest of the year and I’m not going to go into that debate. We’re definitely in a better position than what we were.”

Whincup has endured a hot and cold start to the season and attributed his return to form to the five-week break and a recent test session at Queensland’s Willowbank circuit.

“We’ve come out with a completely different car to what we had at the start of the year and full credit to the guys,” he said.

Limited tyre allocation has been the talk of the paddock in Darwin. For the first time this season each driver has been allocated only four sets of tyres - two with hard-compound rubber, the other two with a soft compound - for  the round. While the "hards" can be used at any point over the weekend, the "softs" can be used only during Sunday’s race.

The track surface at Hidden Valley is at the end of its grip life, making consistently fast laps a challenge. Hot weather is a constant challenge too, with temperatures predicted to reach 32 degrees on Sunday.

Whincup and Lowndes have taken comfort in most drivers confronting the same tyre limitations.

“The thought of having to put those tyres back on the cars again tomorrow is mind-numbing,” Whincup said.

“I think we should have had six sets. Five would have been better still, but four is very difficult.”