Lewis Hamilton was let down by his Mercedes yet again as Nico Rosberg romped to pole position at the Russian Grand Prix.

A tight tussle for top spot on the grid had looked likely as the championship-leading pair fought for first place in the first and second qualifying sessions.

But Hamilton did not emerge for Q3 due to a repeat of the electrical issues that forced him to start at the back of the grid last time out in China.

"It's a second engine that I took at the last race and same failure as I had in the last race," Hamilton explained to Sky Sports.

"I went back out in Q2 at the end to just get a feel of the lap and I lost the same power as I lost in China.

"There's nothing I can do, but I never give up."

Rosberg had broken the Sochi Autodrom track record with a flying lap of one minute and 35.337 seconds in Q2, but 1:35.417 was enough for pole in the top-10 shootout.