Like a distance runner coming off the final corner with more of a kick than anyone else, Red Bull's Formula One world champion Sebastian Vettel has made his move and hit the front in the title race.

Whether he can make it stick down the home straight, the last four long-haul races, depends on how Ferrari and Fernando Alonso respond after the German forged six points clear in South Korea with his third successive win.

Barring misfortune in this most unpredictable of years, the drivers' championship has now become a straight fight between two rivals vying to become the sport's youngest triple titleholder.

McLaren's Lewis Hamilton and Jenson Button, both champions, recognised they were out of the reckoning after a nightmare afternoon for the British team at the Yeongam circuit.

"I think it's over for both of us," said Button, sixth overall and 84 points off the pace. "The constructors' is also difficult for us as a team but still possible if Red Bull have a bad weekend."

Hamilton, fourth and 62 points behind Vettel, after finishing 10th on Sunday, agreed: "I don't see us in the fight. It's out of the question for us probably now."

Finland's Kimi Raikkonen is third overall for Lotus, but the 2007 champion is 48 points off the lead and without a win yet this year.

In 2010, Vettel left it until the last race in Abu Dhabi to snatch his first title from under Alonso's nose. Last year, he led all the way and wrapped up his second with four races to spare.

This season the 25-year-old has taken a different route, leading early in the campaign and then losing the advantage before again asserting himself with four races to go, but the eventual outcome could be the same.

"We've hit a purple patch of form at the right time, but it's important we maintain that now," Red Bull principal Christian Horner said after Vettel led teammate Mark Webber home for the first one-two by any team this season.

"There's still a long way to go," he added after an afternoon of domination that saw the Red Bull drivers turn the timing screens purple - the colour used to indicate a fastest lap.

The fact that it has taken 16 grands prix for any team to extract the maximum points from a race only reinforces how competitive the season has been.

The first seven races were won by an unprecedented seven different drivers but Red Bull's run of form now has an ominous predictability to it.

"We can see how quickly it can turn around. it can just as easily go the other way with us and Ferrari," Button said.

"That's not the worry. The worry is how far Red Bull are ahead at the moment in the championship and also how strong they are. They are consistently winning and also getting very good points."

Ferrari, who had Alonso four points clear before the Korean weekend saw the 31-year-old Spaniard lose the lead he had held since June, refused to be downcast.

"Anyone who thinks that losing the lead in the drivers' championship might leave us discouraged is making a big mistake," said Ferrari principal Stefano Domenicali, whose team overtook McLaren to go second in the constructors'.

"Clearly at the moment Red Bull might seem unbeatable in everyone's eyes, but I can remember the same thing being said about McLaren on (the) Sunday afternoon in Singapore. The wheel turns quickly this year."