Red Bull Racing and Lotus have asked the FIA to reconsider its view that the Mercedes DRS-activated F-duct is legal, with sources suggesting that an official protest cannot be ruled out.
On a weekend of major interest about the design of the Mercedes rear wing, which makes use of a hole to help flow air to either the wing itself or the diffuser to stall them for a straight-line speed boost, rival outfits are now uneasy about the situation.
AUTOSPORT can reveal that representatives of Lotus and Red Bull Racing approached the FIA's head of the technical department Charlie Whiting before final practice in Melbourne on Saturday morning to discuss the matter.
Neither outfit was willing to comment officially on what was discussed, but sources have suggested that the issue revolves around Articles 3.15 and Articles 3.18 of the Formula 1 Technical Regulations.
Article 3.15 states: "With the exception of the parts necessary for the adjustment described in Article 3.18, any car system, device or procedure which uses driver movement as a means of altering the aerodynamic characteristics of the car is prohibited."
Article 3.18 covers the specifications and components for the DRS elements of the rear wing, with Red Bull Racing and Lotus arguing that there is no part of the rules here that would allow the F-duct type system Mercedes is understood to be running.
Whiting said earlier this weekend, however, that he could see nothing in the regulations that would outlaw the Mercedes wing - as it was totally passive.
"What it appears some teams are doing is that when the DRS is operated, it will allow air to pass into a duct and do other things," he explained.
"That is all I can say - you will probably have a pretty good idea of what it might be doing, and other teams will as well. But it is completely passive. There are no moving parts in it; it doesn't interact with any suspension. No steering, nothing. Therefore I cannot see a rule that prohibits it."
It is possible that Whiting could issue a clarification of the matter, as he did before the start of the system on the Lotus reactive ride design that was outlawed on the basis it was providing an aerodynamic benefit.
However, if Whiting stands firm on his belief the Mercedes wing is legal, then Red Bull Racing and Lotus would have the option of lodging a protest about the wing after qualifying for the Australian Grand Prix.