Sebastian Vettel moved a step closer to his third world title with victory in Korea as Lewis Hamilton saw his challenge extinguished in Yeongam.

The McLaren driver entered the race 42 points off the top of the drivers' championship and needing to make up some ground to keep himself in the hunt.

But the race proved a nightmare for the 27-year-old as he finished 10th and fell 62 points behind new championship leader Vettel, who overtook Fernando Alonso with his fourth win of the year.

A rear anti-roll bar failure during his first stint ultimately proved to be Hamilton's undoing.

The problem meant an extra pit stop for fresh rubber with the resulting handling problems causing high levels of tyre degradation as he dropped back from an initial fourth place.

The problem was exacerbated when a loose piece of Astroturf became attached to his car during the closing laps, and he ended up just holding off Sergio Perez, his McLaren replacement for 2013, for the final point.

And Hamilton admits his chances of departing McLaren for Mercedes as a world champion are finished.

He said: ''I think in terms of winning that is it for us, but I think we can still get a lot of points.

''We are 62 points behind now so it is going to be tough.''

He added: ''I don't see us in the fight. It's out of the question for us probably now, it's a shame as we were right there for a moment but this is motor racing. It's a sad day, but we will live.

''I feel a little bit exhausted. It was a tough race, I tried my best, we had another problem at the back of the car, I don't know how.

''But the team said it was safe to drive and I kept pushing as much as I could but the balance was changing from corner to corner. The car was moving all the time, even on the straight.

''It's a day to forget, this has been a year to forget as well so I am looking forward to a fresh start next year.''

There were few problems for Vettel, however, as the German took his third win in a row - and the 25th of his career - to open a six-point lead over Alonso.

Vettel now tops the standings for the first time since May, and given the pace of Red Bull here and in Japan last weekend, he is the clear favourite to emerge as champion.

The key to the German's victory was his start, as he got away well from the dirty side of the grid to overtake pole-sitting team-mate Mark Webber into turn one and secure a lead he was never to relinquish.