The Red Bull driver secured a third win on the trot on Sunday and in doing so leapfrogged Ferrari's Fernando Alonso at the top of the drivers' standings, in what looks like a two-horse race now for the title.
The chasing McLarens of Lewis Hamilton and Jenson Button endured a dreadful weekend at Yeongam. Hamilton was 10th while his fellow Briton was dumped out the race moments after the start by an apologetic Kamui Kobayashi.
Hamilton and Button, both former world champions, admitted afterwards that their assault on the crown was over. Kimi Raikkonen, of Lotus, is third in the championship but a hefty way behind the two at the top of the pack.
Vettel, who is going after a third title on the bounce, tops the charts with 215 points, the Spaniard Alonso is on 209 and Raikkonen back on 167. The next grand prix is in India in two weeks.
"For many months it was something of a real roller-coaster ride, but we finally found our strength again and since Singapore it works," said the German Vettel, after he and Mark Webber took a Red Bull one-two in South Korea.
"Today the team did everything right, and I didn't do anything stupid -- we sure want to keep it that way."
Singapore last month began a sequence of imperious victories for Vettel that saw him close the gap on Alonso, also a double world champion, before usurping him Sunday. Alonso was third in the race, his team-mate Felipe Massa fourth.
But the 25-year-old Vettel said nobody at Red Bull was getting carried away.
"What I think is important is that we have to keep things simple. That means that we have to concentrate on ourselves because we cannot influence what others are doing and starting mind games now about what others will do in the next races is a waste of energy," he said.
"Lately we had some pretty good races and of course I hope that we will be able to continue in that way. But it is also obvious this season that things can change quite fast, so there is no guarantee that luck will stay on our side. So 'keep on pushing' should be our motto for the last four races."
Ferrari, who have now overtaken the fast-fading McLaren team in the constructors' championship, refused to sound disheartened by Vettel's fine run of form.
It is no secret that the Red Bulls are the quickest cars in the field, but in Alonso the Italian outfit have a highly skilled driver who has seen and done it all before. He has consistently got the most out of his inferior Ferrari.
"It's true that Red Bull was quickest all weekend, but our aim was to be right behind them and we achieved that," said the 31-year-old.
"It's also true that I am no longer leading the championship, but being six points down does not mean much, just as it did not mean much being four points up going into this race."
He added: "There are a hundred points up for grabs and everything will depend on how much we can improve over the coming races.
"Here we were much closer to the lead than we were in Singapore and nearer than in Suzuka (in Japan, the race before Korea), so we must continue in this direction.
"Vettel's three wins in a row? Well, he and Red Bull have had three perfect weekends so congratulations for that, but when everything goes smoothly for so long, inevitably sooner or later something has to happen.
"We are right in the fight for the title with a car that has never been the fastest. It seems we are capable of doing something good too, don't you think?"