Adrian Newey has reportedly submitted a letter of formal resignation to Red Bull after becoming unsettled in the wake of the Christian Horner saga. The departure of the esteemed chief technical officer could be confirmed by the reigning constructors' champions ahead of the Miami Grand Prix this weekend.

Notions of Newey's discontent first emerged last week, with the 65-year-old said to be unhappy with the working environment at Red Bull after controversy involving team principal Horner, who was accused of inappropriate behaviour by a female colleague.

Horner always denied wrongdoing and he was cleared by an independent inquiry. But now, Motorsport.com claim that Newey has decided to formally resign from Red Bull following talks with the team.

Attention behind the scenes will now turn to the terms of Newey's exit amid the prospect of him joining one of Red Bull's rivals. Ferrari and Aston Martin are both believed to be interested in making a move for the man widely considered to be the greatest F1 car designer ever.

Newey, who is set to remain in his chief technical officer role for the time being, reportedly communicated his decision to Red Bull with a letter. The Horner saga and the ensuing power struggle at the top of the team is thought to be a decisive factor.

Max Verstappen's dad, Jos, publicly called for Horner to step down after WhatsApp messages allegedly from the team principal to an unnamed person were leaked to journalists. There is also understood to be tension between Horner and Verstappen's mentor, Helmut Marko.

Hints of a fractured relationship between Newey and Horner can be traced back to last year, when Horner played down the design chief's importance to his team by referencing Manchester United's success after their talisman, Eric Cantona, departed in 1997. Newey's wife, Amanda, slammed the interview on social media.

Last week a Red Bull spokesperson said they were 'unaware of Newey joining any team', with his contract set to run until the end of 2025. However, the latest development means they could release a statement before the Miami Grand Prix this coming weekend.

Ferrari is said to be the outgoing Red Bull man's preferred destination after nearly joining the Scuderia several times earlier in his career. A move would see him link up with seven-time world champion Lewis Hamilton, who is heading to Maranello next year.

Aston Martin have also offered big money and Mercedes could join the hunt, but Newey reportedly has reservations about working with the former team's owner, Lawrence Stroll, and the latter's team principal, Toto Wolff.