Christian Horner has insisted Adrian Newey’s shock departure is not the reason behind Red Bull’s sudden collapse – after Max Verstappen claimed he is now powerless to stop McLaren’s Lando Norris from winning the world championship.

Verstappen accused Red Bull of turning the car that last year carried him to a third successive title into a monster following Sunday’s Italian Grand Prix.

Norris failed to convert his pole position in Monza into a victory after he finished third, but the British driver was still able to take eight points out of Verstappen’s championship lead after the Red Bull man qualified seventh and only improved one place in the race.

Verstappen is now on a streak of six grands prix without a victory, while Red Bull have claimed just three wins since Newey – the British mastermind behind Verstappen’s recent dominance – announced he was leaving ahead of the Miami Grand Prix on May 5.

Newey’s exit came in the wake of the Horner scandal which rocked Red Bull, and the sport, ahead of the season.

Red Bull have always insisted his departure was not linked to a female member of staff accusing Horner of controlling behaviour. Horner has always denied the allegations, and he has twice been exonerated by the F1 team’s parent company, Red Bull GmbH.

“We would have had all of these issues because the issues were already there, and one man’s input could never be so dramatic so quickly,” said Horner when asked if Red Bull are missing Newey’s stardust.

“This started to really highlight itself in Miami, and Adrian was plugged in up until Friday of Miami, so there’s no way it would have been impacted so quickly.

“Formula One is a team sport, it’s a team issue, and the team will come up with a resolution.”

Verstappen raced to seven victories from the opening 10 rounds, but Norris and McLaren are ready to strike with Red Bull’s struggles leading the 26-year-old Dutchman to say it is not realistic he will defend his title.

Verstappen is 62 points clear of Norris with 232 points still to play for. Red Bull are just eight points ahead of McLaren in the constructors’ standings.

“Based on the performance in Monza, you’d say both championships are under absolute pressure,” added Horner. “We were the fourth fastest team, and that’s the reality.

“We are under pressure to turn it around and nobody puts us under more pressure than ourselves because finishing six hurts. If we want to make sure we win both titles, we’ve got to put performance on the car.”