Niels Wittich has left his role as Formula 1's race director with immediate effect.
The German, a replacement for Michael Masi in 2022, "has stepped down from his position to pursue new opportunities," the FIA said in a statement.
He will be replaced from the next race in Las Vegas by Rui Marques, most recently the race director for Formula 2 and 3.
It is highly unusual for an F1 race director to be changed in the middle of a season, especially given there are just three races remaining although some insiders had heard Wittich would be replaced at the end of the season.