Questions over the design of the diffusers have surfaced since Williams and Toyota appeared to exploit the wording of the regulations to allow themselves a taller design than the rules originally intended.
But the debate has stepped up a gear after Brawn GP's new car, which features a unique twin-deck concept, has dominated pre-season testing times.
With the matter still not settled, and talk of a possible protest having surfaced in recent days, Red Bull's advisor Helmut Marko has now confirmed his team will object to the design if it is unchanged and given the all-clear by scrutineers.
Speaking to Gazzetta dello Sport about the design of the Brawn diffuser, Marko said: "It's illegal: we'll make a protest on Thursday if the component isn't modified to conform to the regulations, because that diffuser guarantees a five-tenths-advantage per lap. Seven teams are certain it's illegal."
FIA president Max Mosley revealed earlier this week that he expected the matter to reach a head in Australia, having received complaints from at least one team about the diffuser design.
"If there had been more time before the detailed objections to the system were sent in, I would probably have sent it to the FIA Court of Appeal before Australia," Mosley told the Daily Telegraph.
"And actually I have given thought to that this week. But there isn't time. It wouldn't be fair. I think the thing will probably come to some sort of a head in Australia."
As technical analysis of a car revealed, the diffuser is a unique double-decker design where the U-shaped centre section becomes the lower deck of the set-up, rather than the roof.
Brawn GP was unavailable for comment on Tuesday night in Melbourne, but Rubens Barrichello told Gazzetta dello Sport that he was unmoved by the controversy about the team's diffuser.
"I wasn't bothered by the fact that everyone took for granted that [Bruno] Senna was replacing me, so do you think I'm bothered by the fact that my car is different from the others?" he said.
"We've read the rule book differently, and the result of that can be seen by everyone."