Championship leader Max Verstappen, riding a wave of 10 wins in a row, qualified only 11th while Mexican team mate and closest title rival -- albeit 145 points behind -- Sergio Perez was 13th fastest.

Red Bull had been in a league of their own previously, winning every grand prix this season and 15 in succession dating back to last year, but Ferrari and Mercedes secured the front row slots for Sunday's night race.

"It's very, very confusing. To have dropped the amount of pace that we have," Horner told Sky Sports television.

"The car's just not responding to changes, you can hear this understeer, oversteer, braking issues -- it's like we haven't managed to get the tyre into the right working window.

"The car we have here for qualifying is essentially the identical car that we had two weeks ago in Monza and a week before that in Zandvoort," he said when the technical directive was mentioned.

"Nothing's changed on the car. We tried a new aero part on Friday and we thought OK we'll revert on that component, so it's a tried and tested set-up that we have. But it just hasn't responded on this circuit, on this asphalt."

The directive, TD018, was introduced from this weekend after the governing body's technical director Tim Goss saw "a little bit too much freedom being applied to the design details of aerodynamic components."

Directives are advisory and while they do not constitute part of the technical regulations they are key to how the FIA applies the rules.