Mercedes swaps Hamilton to spare engine

Reigning world champion Hamilton encountered an identical MGU-H problem to the one that affected him at Shanghai when he headed out on track for the second time in Sochi Q2.

Mercedes carried out investigations overnight and has decided to fit his original Melbourne engine, which was used in the subsequent two races.

The world champion team says its approach was guided by the fact it did not want to break parc ferme conditions so Hamilton can start 10th rather than from the pitlane.

The engine fitted to the car has a new turbocharger and MGU-H - his third of the season as they were replaced after the China failure.

Mercedes has also replaced the control electronics and energy store as it bids to eliminate those parts as a potential source of the problem.

The situation was complicated because Mercedes introduced an fuel system upgrade for Russia, having used two tokens, and did not have spare components on site.

The team says it flew out a fuel system on a chartered jet on Saturday evening. It arrived in the early hours of the morning, and the spare engine - which is not covered by parc ferme rules - was fitted with the new parts.

When the car was removed from parc ferme on Sunday morning, the spare was fitted and Mercedes says it has been fired up successfully in the garage.