Lewis Hamilton does not know why Mercedes switched a large portion of his team of engineers with team-mate Nico Rosberg's, but denied suggestions of favouritism.

Hamilton's car has been wrought with technical issues this season, with electrical problems that forced him to start from the back of the grid in China rearing their head again at Russia, leaving him 10th after qualifying.

The defending world champion managed to work his way up to second position in Sochi, but he fell short of applying pressure on Rosberg who maintained his 100 per cent record this season.

Hamilton admits he does not understand why the "majority" of the staff who helped him to two straight drivers' titles in 2014 and 2015 have been moved across to his team-mate, but he does not put it down to Mercedes' partiality.

"All I can say is that my side of the garage are having a hard time. I have every confidence and faith in them," he told Sky Sports.

"It's unusual for them - the majority were on Nico's car last year and Nico's guys were with me for three years. We swapped for no apparent reason but that is not the reason we're having issues.

"Don't jump the gun. It's not happened in the last three years [favouritism] and I have no reason to think that's happening now."

A water-pressure issue stopped Hamilton hunting down Rosberg in the latter stages of the race, leaving him happy just to have finished.

"It happened and I had to nurse it home," he continued.

"I'm just happy the car finished. It was another issue leading to a failure. I've got a long way to go with not a lot of engines."