Nico Rosberg believes the race for the Formula One drivers' championship is far from over, despite Mercedes team-mate Lewis Hamilton extending his lead to 48 points in Japan.

Hamilton's victory at Suzuka last month was his eighth triumph of 2015 and moved him a step closer to becoming world champion for a third time in his career.

The Briton's advantage means Rosberg needs a positive result at the Russian Grand Prix this week, but he remains hopeful of catching his rival over the final five races of the season.

"I'm not backing down in my fight for the championship and gaining those positions back fair and square showed that," the German said. 

"We have five races to go and, although the championship gap to Lewis is quite big, in my mind it's definitely not over yet.

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

Meanwhile, 2014 Russian GP winner Hamilton is focused on maintaining the form that has seen him win three of the last four grands prix by securing back-to-back successes in Sochi.

He added: "Suzuka was a really special weekend for me and another fantastic result for the team. 

"Everyone is doing such an incredible job once again this season and every bit of this success is well deserved. 

"The car was unbelievable to drive in Japan, so hopefully it'll be more of the same at the remaining races - starting in Sochi."