Both Toro Rosso drivers will receive grid penalties at this weekend's Russian Grand Prix as engine supplier Honda introduces a new power unit upgrade.
The Japanese manufacturer is hopeful that the latest specification will offer "more performance in the long term" and comes one race ahead of its home grand prix at Suzuka. However, the changes in power unit components mean both Pierre Gasly and Brendon Hartley will start towards the back of the grid with penalties this weekend in Russia.
Next year, Honda will supply Red Bull with engines and the Sochi update is believed to form the basis of the 2019 power unit.