Robert Kubica will start Sunday's Russian Grand Prix from the back of the grid after receiving a penalty for changing multiple elements on his Mercedes power unit.

Williams driver Kubica had been in line to rise up the field after it was confirmed on Thursday that all four Honda-powered drivers would be taking penalties for engine changes, with Daniil Kvyat falling all the way to the rear of the field.

But Kubica will join Kvyat on the final row of the grid after Williams confirmed the Pole would be moving to the updated-spec Mercedes engine in Russia, triggering a penalty for the fourth usage of the season, exceeding the season limit.

On top of the regular penalty for a new engine, Kubica has also received a new turbocharger and MGU-H, resulting in a 'back of grid' penalty from the FIA.

Williams has confirmed that George Russell will also move on to the new Mercedes engine, but will do so without a penalty.

Kubica's penalty means that one-quarter of the field now has a grid drop, but Max Verstappen, Alexander Albon and Pierre Gasly are all due to fall only five places as they have each taken a fresh engine and no other elements.

Kubica is currently trying to secure a new racing programme for 2020 after confirming his exit from Williams at the end of the year, but said his focus remains on the current race weekend before working more on his future in the gap between Russia and Japan.

"I’m focused, both Singapore and here," Kubica said. "Of course after the race there will be a few days where I will have a bit more time to think about and see.

"Then we will move forward I think in the next weeks, but we will see."