Supercars champion Scott McLaughlin's racing rivals say his 2019 title will be forever tainted and have compared the Kiwi to disgraced cyclist Lance Armstrong.
Ford star McLaughlin was sledged fiercely on social media by Holden duo Scott Pye and Nick Percat on the eve of the season-ending Newcastle 500.
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But McLaughlin was defended by another competitor, with Cam Waters calling the shocking comparison to drug cheat Armstrong as "s**t" behaviour.
Pye landed the first blow on Instagram when he posted an article quoting McLaughlin saying he was "annoyed" with his peers after the fallout of his Bathurst sanction for using an illegal engine.
"Tired of seeing this rubbish. As one of his 'peers', I've never spoken to Scotty about this or been critical of the team," Pye said.
"But you must understand that some people are going to be pissed off that a car and team that's been constantly found to be illegal continues to get meaningless penalties.
"Not saying you wouldn't have won, clearly doing a great job but who knows. It will forever be tainted."
McLaughlin took exception to the "constant" accusation and said he'd won 18 races this season with a legal car.
"We were found once of a technical infringement in one qualifying out of 325 times being scrutineered," McLaughlin said.
"So now you understand why I believe this is how our title hasn't been tainted."
Lance Armstrong comparison crosses the line: Waters
Pye then compared McLaughlin to Armstrong, who was stripped of seven Tour de France titles after admitting to years of doping.
"Even if it was once, that's enough to bring everything into question. Lance Armstrong (most-tested athlete) was caught once, but it ruined his whole career," he said.
Percat jumped in with "you've hit the nail on the head" in reference to the Armstrong sledge.
Ford gun Waters said the comments were extreme and unnecessary after he finished second on Friday in practice.
"It has nothing to do with any of that (doping)," Waters said.
"I love banter but that's s**t. It shouldn't be said.
"What's happened with the engine stuff was pretty minute. It's happened - move on."
The drivers will resume their on-track rivalry on Saturday in qualifying.