Former McLaren technical boss James Key has joined Alfa Romeo in the same role, the team announced on Wednesday.
Key, who left McLaren shortly after the start of the season, will begin his new role in September, replacing Jan Monchaux.
The move marks a return to the Swiss-based Sauber operation, which currently races under the Alfa Romeo brand, where Key was technical director between 2010 and 2012.
It also reunites Key with another former McLaren colleague in Andreas Seidl, who last year left the British outfit to become Sauber CEO.
Seidl has been tasked with preparing the Swiss operation for the start of its partnership with Audi in 2026.
While Audi will build its power unit in Neuburg, Germany, Sauber will be in charge with developing and manufacturing the the Audi team's race car at its Switzerland HQ.
Seidl said Key will be vital in the success of that new era.
"I am delighted to welcome James back home to Hinwil as he joins us to shape the future of this team," Seidl said.
"The operation he will find has changed a lot since his time here, but the same drive, the same commitment that contributed to making the team successful in his previous experience are still the same.
"I am sure that, together with this very talented and committed team, we will be able to continue on the path of growth on which we have embarked.
"James's appointment is a crucial step on this journey. He has an outstanding amount of experience in the sport, not just as technical director, but also in various other roles within the technical organisation of a team.
"He will lead the transformation process of the technical side of the team, giving us the tools and direction we need to tackle the future.
"I also want to thank Jan for his precious contribution to taking Sauber to where it is now, following our most successful season in a decade, in which we climbed to sixth place in the Constructors' Championship."
Key started his career with Jordan and stayed with the team as it became Spyker and Force India, before joining Sauber in 2010.
He joined Red Bull junior team Toro Rosso in late 2012 where he forged a reputation as someone who could build good cars on a limited budget.
Key joined McLaren at the start of 2019. Despite McLaren scoring a victory at the 2021 Italian Grand Prix, the failure of 2022 and the slow start in 2023 eventually saw him and the team part ways.