Nico Rosberg's world championship title dream appears all but over after the German's Mercedes limped out of the Russian Grand Prix on Sunday.

Rosberg, who trailed his teammate Lewis Hamilton by 48 points arriving in Sochi, started from pole and was leading the defending world champion before a fatal throttle problem forced him out of the race on lap seven.

Before retiring he had told his mechanics on the team radio:  "The throttle pedal is broken. If it sticks, what should I do?"

If Hamilton goes on to win the race he would take a 73 points lead over Rosberg with only 100 points of the season left to play for.

Back in the pits a visibly disappointed Rosberg told the BBC: "Straight after the safety car the pedal broke. It was quite dangerous. Definitely not a nice way to end the day."

Asked what this retirement meant for his title ambitions he shrugged: "I don't know, it's made it more difficult of course.

"But I was never going to win a championship like that when normal things break.

"But of course I'll come back like I always do to keep pushing."

Source: AFP