Sochi, Oct 5 (IANS): Mercedes' German driver Nico Rosberg says he has not given up hope of beating teammate Lewis Hamilton to the Formula 1 title ahead of Sunday's Russian Grand Prix.

Rosberg, who finished second to Hamilton last time in the Japanese GP, trails the defending champion by 48 points with five races left this season. Mercedes lead Ferrari by 169 points in the constructors' championship.

"I'm not backing down and in my mind it's not over yet," Rosberg, who is 11 points ahead of Sebastian Vettel, was quoted as saying by BBC on Sunday.

Second-placed Rosberg, who has won three GPs this season to Hamilton's eight, said: "The gap on Lewis is quite big.”

"But the way the whole team has performed this year -- from the factories to the garage -- has been just incredible. I have the car I need to get back to the top step," Rosberg said.

Hamilton led Rosberg home in Russia last year to clinch the 2014 constructors' title for Mercedes.