Palmer announced on Saturday after Japanese GP qualifying that the Suzuka race would be his last event with the team, after weeks of uncertainty about his future.

The move cleared the way for Sainz to replace him at Renault, meaning Gasly - who was originally only expected to do two races with the team - could be retained for the remaining grands prix.

Toro Rosso has confirmed Gasly will remain at the team in Austin and will skip the Suzuka round of the Super Formula series.

Daniil Kvyat, who lost his seat to the Frenchman for Singapore and Japan, will return to the Faenza squad for the Austin event.

"I would like to thank Carlos for all his efforts over almost three Formula 1 seasons," said Toro Rosso Franz Tost. "He always did his very best, demonstrating an excellent attitude and commitment to his work, which helped him and us to get some great results during that time.

"Therefore, on behalf of everyone at Toro Rosso, I wish him all the very best with his new team. We look forward to beating him on track!"

Sainz, who will be loaned by Red Bull to race for Renault in 2018, added: "First of all I would like to thank Toro Rosso and Red Bull for allowing me the possibility of finishing this season with Renault Sport Racing.

"More specifically, I really want to thank all my engineers and mechanics for their support and tremendous work throughout these years.

"Toro Rosso is made up of a fantastic group of people and I wish them only the best for the future. On my side, I will definitely do my very best in tomorrow's race... this would be the best possible send-off!

"Additionally, competing in these last four races with Renault gives me a good opportunity to get to know the team and the car earlier than expected. I am looking forward to start working with them."

Renault said that Briton Palmer and the team had decide to end their relationship by "mutual agreement".

"I would like to thank Jolyon for his commitment to the team and his professionalism," said team boss Cyril Abiteboul. "Since Renault's return to Formula 1, Jolyon has been highly dedicated in an evolving environment.

"He has shown great personal qualities and we wish him all the best in his future career."

Palmer added: "It's been an extremely challenging season and I've been through a lot in the last three years, but it's been a tremendous journey overall with the team.

"I can look back proudly at the performance in the second half of last season, my first point in Malaysia and of course reaching a career high of sixth place in Singapore this year.

"I wish the team all the best for the future. My immediate focus is now on achieving the best possible result in the Japanese GP, and then I can assess my options for the future."