Raikkonen has a massive deficit to make up if he is to retain his title

World champion Kimi Raikkonen has admitted that he no longer has control over whether he can retain his title.

The Ferrari driver is 21 points adrift of championship leader Lewis Hamilton with a maximum of 40 points available in the remaining four races.

"The most important thing is to win again," the Finn said in the build-up to Sunday's night race in Singapore.

"In theory, the championship is not over yet but I don't have it under control any more."

Raikkonen admitted his hopes of winning the world championship depended on some misfortune befalling his team-mate Felipe Massa and Hamilton, who has a one-point lead over the Brazilian.

"The situation in the championship is what it is and it doesn't depend any more only on my results but on my competitors' results," he added.

Raikkonen has not won a race since the Spanish Grand Prix in April, but he can take solace from the fact that he won last year's title thanks to an astonishing late-season charge, when he made up a 17-point deficit on Hamilton in the final two races.

Driving on a street circuit is pure emotion Kimi Raikkonen

The 28-year-old's form has not been good for much of the summer, and he has not scored any championship points since July, when he was sixth in Germany.

"We'll give it our best at Singapore, so that we can fight for the win, which still remains the main objective," Raikkonen said.

"We have to give it our all in these four races and then we'll see what's going to happen.

"I've said it many times - victory is the only objective, the essence of motor racing. I'm not just here for driving. I want to win."

The Singapore track is a street circuit around the heart of the Asian city state and Raikkonen's form on similar tracks this year has been poor.

A mistake took him out of contention at the season opener in Australia, he was not a contender for victory in Monaco, was outpaced by Hamilton in Canada, and was off the pace again in Valencia.

"When I think of the results I had this year on street circuits, I shouldn't be too optimistic," he said of his chances on Sunday, "but I still like to race on this kind of track.

"It's pure emotion, when you find the right set-up for the car and race between the walls."

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And he said the unusual timings of the event would not cause him any problems.

With Saturday's qualifying session and Sunday's race being held late at night in Singapore, the drivers will go to bed in the early hours and wake up at lunchtime.

There have also been concerns that if it rains, the powerful floodlights could cause visibility problems.

But Raikkonen said: "I don't think it will be a big problem that we race at night. They've done it already with motorbikes and it was a great experience.

"I'm someone who likes to sleep late. My body will adapt perfectly fine to the unusual time of day."