Mercedes boss Toto Wolff has called Red Bull's Christian Horner a "wind bag" for comments he made about his team's car ahead of the Azerbaijan Grand Prix.
The threat of protests hangs over the race in Baku this weekend, with Red Bull's "bendy" rear wing the centre of attention.
Formula One's rules say all components influencing a car's aerodynamic performance must be rigidly secured and remain immobile.
Horner has been robust in his defence of Red Bull and, during the build up to Sunday's race, said there should be equal scrutiny given to Mercedes' front wing.
Talking to Sky Sports on Friday, Horner said: "I think if I was Toto with the front wing he's got on his car, I'd keep my mouth shut."
Horner was referring to an onboard shot of the wing clearly flexing when the car hit the braking zone.
He added: "A lot of noise has been made about the rear wing, and a lot of revisions have had to be made.
"So if you're picking on one end of the car, you have to look at the other. You can't look at one part in isolation and say that set of rules only applies to that element on that car.
"You have to look at all areas. Sometimes, you have to be a little bit careful what you wish for."
Ahead of qualifying on Saturday, Wolff was asked what he made of Horner's comments.
"Christian is a bit of a windbag who wants to be on camera," Wolff said. "It's easy to be punchy when you're on the top of the times sheets but you should be a little bit more modest."