Pierre Gasly and Brendon Hartley will drive for Toro Rosso at this weekend's Mexican GP.
It means that Daniil Kvyat has been sidelined despite his point-scoring return to action at the US GP when he finished tenth with a performance he described as "my best of the season".
The Russian was previously dropped for the Japanese and Malaysia GPs when Gasly debuted alongside Carlos Sainz.
Sainz has since joined Renault while Hartley made his bow at Austin alongside Kvyat when Gasly was due to compete in the Super Formula season finale - an event which was then cancelled due to bad weather.
Hartley finished 13th on his F1 debut in his first single-seater race since April 2012.
When's the Mexican GP on Sky F1
All of Toro Rosso's 2017 results
'Scuderia Toro Rosso's Driver Line-Up for the upcoming 2017 Mexican Grand Prix will be formed by the following pairing: Pierre Gasly and Brendon Hartley,' the team confirmed in a one-line statement which offered no further insight into Toro Rosso's plans for the final two races of the season.
The team have changed line-up in each of the last three races and are yet to confirm either of their two drivers for 2018 when they will be powered by Honda.
See if Lewis Hamilton can clinch his fourth world championship at the Mexican GP exclusively live on Sky Sports F1. Sunday's race begins at 7pm. Want to watch but not got Sky F1? Buy a NOW TV pass from £6.99!