Brendon Hartley is poised start his first Formula 1 race from the back of the grid after Toro Rosso opted to take a number of new power unit elements on the New Zealander’s car for the United States Grand Prix, with a penalty set to be confirmed shortly.

Hartley was brought in by Red Bull to race for its B-team after Pierre Gasly was ruled out due to commitments at Suzuka in Super Formula, with the Porsche factory driver getting his first taste of an F1 car since 2012 in practice on Friday at the Circuit of The Americas.

Toro Rosso opted to take a number of new power unit elements on Hartley’s car ahead of this weekend’s race in Austin, triggering a grid drop for the Porsche factory racer.

FIA technical delegate Jo Bauer confirmed in his pre-race report that a new internal combustion engine, MGU-H, energy store and control electronics had been fitted to Hartley's power unit, totalling a 25-place grid penalty.

Hartley is set to be joined towards the rear of the field by Renault's Nico Hulkenberg, who is set for a 20-place drop after taking a new ICE, turbocharger and MGU-H, while Stoffel Vandoorne is due to drop five places after McLaren used an eighth ICE of the year on his Honda power unit.