Former Indianapolis 500 winner Gil de Ferran has left his role as sporting director of the Honda Formula One team.
De Ferran had become unhappy with his position at Honda
The Brazilian said he was leaving after two years because the role had not developed in the way he had wanted.
De Ferran said: "My decision was not easy. I simply feel that I came to this team to fulfil a particular role and it has not materialised as I had hoped."
Honda F1 boss Nick Fry said De Ferran had become "increasingly uncomfortable" in the team.
De Ferran, whose decision ends a relationship with Honda stretching back more than 10 years, will pursue unidentified "other opportunities".
The Japanese car company supplied the engines to the cars in which De Ferran won back-to-back Champ Car titles in 2000 and 2001, and the Indy 500 in 2003.