Lewis Hamilton admits he faces another tough race day after a second ERS failure in as many qualifying sessions left him down the order ahead of the Russian Grand Prix.

Already facing a sizeable 36 point deficit to Mercedes team-mate Nico Rosberg in the overall standings following the German's three straight wins, Hamilton has been hampered by a series of misfortunes this year, from turn one clashes to technical issues.

The latest problem stems from the ERS yet again, which forced him out of qualifying at the previous Chinese Grand Prix, leaving him last on the grid.

Though this time he would be forced to stop at the beginning of Q3 - thus placing him a provisional tenth on the grid - Hamilton says the limited overtaking opportunities of the Sochi Autodrom will make his race hard regardless.

"It was the second engine that I took from the last race and the same failure that I had in the last race. I just went back out at the end of Q2 and I lost the same power as I lost in China."

Though he is listed in tenth place, Mercedes says it remains unclear as to whether he will face a penalty for component changes.