Toro Rosso team principal Franz Tost says a desire for stability allied to Daniil Kvyat being "back on top form" led to his team naming an unchanged driver line-up.

It was announced on Saturday morning in Austin that Kvyat will be retained by Toro Rosso alongside Carlos Sainz in 2017, with the Russian keeping his seat despite being dropped by Red Bull in favour of Max Verstappen earlier this season. While Pierre Gasly had been heavily linked with a drive, Tost says Toro Rosso wanted stability in its driver line-up ahead of new regulations next season.

“It makes a change to announce our driver line-up relatively early," Tost said. "There are so many new elements coming to Formula 1 in general and to our team specifically, in terms of the change of power unit supplier, that having the same two drivers gives us stability and a benchmark to work from.

"For Carlos, it will be his third year with us, which speaks volumes when it comes to how highly we rate him.

"In recent races, it has been clear that Daniil is back on top form. I always told him that his future with us was in his hands and he has stepped up to the mark and delivered the sort of performances that have ensured his 2017 seat in the STR 12.

"We now have a very talented and strong driver pairing to tackle a season in which we expect to be very competitive.”

Toro Rosso has been using 2015 Ferrari power units this season but will switch back to Renault for 2017 and use the latest specification of engine.

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