Red Bull team principal Christian Horner insists a technical directive was not the cause of the difficulties faced in the Singapore Grand Prix, as the team’s run of winning every race this season came to an end. Max Verstappen qualified 11th and Sergio Perez 13th as Red Bull struggled heavily on Saturday, leaving it out of contention on a track that is tough to overtake on. The challenging weekend coincided with a technical directive from the FIA that targeted flexible bodywork – specifically front and rear wings – coming into force, but Horner says that’s no the explanation for Red…