Supercars star Jamie Whincup believes the defection of a Triple Eight stalwart is behind the 2017 rise of rivals DJR Team Penske.
French engineer Ludo Lacroix controversially switched teams after last year's championship, a move Triple Eight Race Engineering boss Roland Dane labelled duplicitous at the time.
Since his switch, DJR Team Penske have gone from also-rans to title challengers, with New Zealand pair Scott McLaughlin and Fabian Coulthard hot on the heels of Whincup in this year's championship race.
Whincup holds a slender 17-point lead heading into this weekend's Auckland SuperSprint event in New Zealand.
It's the first time the six-time champion has held the series lead this season and he admits Lacroix's switch to DJR Team Penske has raised the difficulty stakes for the Red Bull Holden Racing Team.
"All our intellectual property, all the things that made our cars fast was just taken down the road with Ludo," Whincup told AAP.
"We had to start again. He had all the good of Triple Eight and took all the good of the Penske organisation worldwide. It's combined together and that's where that raw pace is coming from."
Whincup still believes the team dynamic at Triple Eight and their experience in closing out championships can prove crucial over this weekend's event and the season final in Newcastle.
Triple Eight has dominated at the 2.91km Pukekohe Park Raceway in recent years, winning five of the past seven races at the circuit.
"There's no substitute for teamwork," Whincup said.
"We've got a great bunch of people that have worked bloody hard over a long period of time and are there to go into battle for each other. That's our biggest strength."
