Formula One world champion Sebastian Vettel led a Red Bull one-two on Saturday in final practice for a Korean Grand Prix he is favourite to win.
The 26-year-old runaway championship leader lapped the coastal Yeongam circuit, near Mokpo and some 400km south of Seoul, with a best time of one minute 37.881 seconds on a bright and sunny morning.
Australian team mate Mark Webber, who will have a 10-place grid penalty imposed after qualifying due to a reprimand he collected in Singapore two weeks ago for getting a post-race ride on Fernando Alonso's Ferrari, was 0.137 slower.
The Mercedes pairing of Nico Rosberg and 2008 world champion Lewis Hamilton, who was fastest in both sessions on Friday, ended up third and fourth on the timesheets.
However Hamilton, unlike the two Red Bulls, did not get a clear lap in on the super-soft tyres and was faster on the harder rubber.
Vettel leads Alonso by 60 points in the standings with six races - including Sunday's - remaining. The German is chasing his fourth win in a row as well as a hat-trick of victories in Korea.
Spaniard Alonso was fifth quickest with a lap of 1:38.486, ahead of Lotus's Romain Grosjean and Ferrari's Felipe Massa.
Finland's Kimi Raikkonen, who crashed his Lotus on Friday and had suffered back pains in Singapore, was only eighth fastest.