Brendon Hartley will retain his seat with Toro Rosso in Formula 1 following his debut in the United States Grand Prix, with Daniil Kvyat making way for Pierre Gasly in Mexico.
Toro Rosso drafted in Porsche World Endurance Championship driver Hartley to replace Gasly last weekend so the Frenchman could try to win the Super Formula title in Japan, while Kvyat returned to the line-up in place of Renault-bound Carlos Sainz Jr.
Gasly, who missed out on the Super Formula title after the finale was cancelled because of the threat of a super typhoon, was expected to return for the remainder of the season.
But the second seat in Mexico was less certain, with Toro Rosso undecided on whether to keep Hartley with an eye on 2018 or retain Kvyat, whose experience would help in its battle for fifth in the constructors' championship.
In a one-line statement released on Monday, Toro Rosso said its Mexican Grand Prix line-up would be formed by Gasly and Hartley but chose not to reveal its plans beyond that.
Kvyat's future in F1 remains uncertain, with the Russian having said he remains confident he can have a future within Red Bull and planned talks with its motorsport advisor Helmut Marko.
Hartley finished his debut grand prix 13th at Austin, in what was his first single-seater race since 2012, while Kvyat finished 10th - only his third points finish of the season.
Toro Rosso trail fifth-placed Williams by 15 points in the constructors' championship but its gap back to Renault in seventh was slashed to five points after former driver Sainz took seventh at Austin.