Pundits in the F1 paddock are casting a suspicious over an area of Ferrari's new-spec SF70H which could contravene technical regulations.
According to German publication Auto Motor und Sport, the focus is on a 'Ferrari flex' story linked to the red car's floor.
An unnamed engineer is quoted as saying: "There are slow motion recordings of Raikkonen in testing, when the floor actually bends downwards at the sides."
Others are less sceptical, saying Ferrari's performance surge in 2017 is entirely legitimate.
"This is not just about the car or the engine, but the whole," said Gunther Steiner, boss of small Ferrari-linked American team Haas.
"Ferrari started developing the car early last season -- earlier than Mercedes," he told Auto Bild.
"And Mattia Binotto is a very, very good technical manager who had a consistent plan from the outset."
Former F1 driver turned pundit Marc Surer, meanwhile, sees the handiwork of another top name.
"The innovative sidepods are typical Rory Byrne," he told German television Sky.
"This year it is also much easier for the drivers to get the car in the right tyre window, which is also typical of Byrne cars."