Sauber technical director James Key is to leave the Swiss team to take up a role with one of its rivals.
In a statement issued by the Hinwil-based outfit on Friday, Sauber said that the design and development of its 2012 car would now be led by the heads of department for its aerodynamic, design, performance and operations divisions.
Key said: "I've enjoyed the past two years working at the Sauber F1 Team. It has been a very intense and interesting time, in which we had to manage the transition from a much larger team to a smaller one, and everybody handled that very well.
"I think the team is now well set for the future and I wish it the very best. I have been offered a new role back in the UK, which I decided to accept."
The identity of the team Key is heading to has not been released, but Key previously worked at the Force India outfit prior to joining Sauber at the start of 2010 as replacement for Willy Rampf.
Team boss Peter Sauber added: "A qualified team shares the overall technical responsibility. This structure has proved to work well at other racing outfits. Over a period of almost two years, James has accomplished a lot for our team.
"Especially in the difficult transition period from a manufacturer team into a private enterprise, he contributed significantly to ensure the team regained stability. We would like to thank him for his efforts and wish him all the best for his future."
Driver Sergio Perez lamented the timing of the move.
"James Key's exit from the team comes at the worst moment, but we have a great team and we will push forward. There's a great year ahead," the Mexican wrote on Twitter.