Steve Nielsen has left his role as sporting director at the Toro Rosso Formula 1 team.
The highly-experienced Briton had worked at the Italian squad since the start of 2013, when he joined after a period at Caterham.
Nielsen has held a variety of roles at major teams during a long F1 career that has included stints at Arrows, Benetton/Renault, Tyrrell and the original Lotus operation.
Toro Rosso declined to reveal the reason for Nielsen's departure.
The team goes into 2015 with an all-new driver line-up, as rookies Max Verstappen and Carlos Sainz Jr replace Red Bull-bound Daniil Kvyat and the ousted Jean-Eric Vergne.