The German will take the title in Japan next Sunday if he wins with Alonso lower than eighth.
Vettel said: "I am really enjoying things at the moment, we have a great team and we are having a great time."
Lotus drivers Kimi Raikkonen and Romain Grosjean took second and third in Korea.
Sauber's Nico Hulkenberg fended finished fourth.
Vettel's title rival Fernando Alonso finished sixth.
Image: © Getty
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