Kimi Raikkonen, of Lotus, is third in the championship but a hefty way behind the two at the top of the pack while Red Bull's Mark Webber is fifth, behind Hamilton.
Vettel, who is going after a third title on the bounce, tops the chart with 215 points, Spaniard Alonso is on 209 and Raikkonen 167.
"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, after he and Webber enjoyed a Red Bull one-two in 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 who gradually closed the gap on Alonso, also a double world champion, before usurping him on Sunday.
Alonso was third in the race, his teammate 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."
Ferrari, who have overtaken McLaren team in the constructors' championship, refused to sound disheartened as the highly-skilled Alonso has consistently been able to get the most out of his inferior car.
"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 Alonso.
