Sebastian Vettel set the fastest time in Friday's practice for the Korean Grand Prix, edging Red Bull teammate Mark Webber and Formula One championship leader Fernando Alonso.
Vettel, who has won the previous two races to move within four points of Ferrari's Alonso in the drivers' standings, was 0.032 seconds faster than Webber at the Yeongam circuit.
Alonso was 0.328 seconds off the pace. McLaren driver Jenson Button was fourth followed by Mercedes' Michael Schumacher and Ferrari's Felipe Massa.
Button's teammate Lewis Hamilton, who was fastest in the morning session, struggled to find speed on the softer tires in the afternoon and finished eighth behind Mercedes driver Nico Rosberg.
Force India's Nico Hulkenberg was ninth while Lotus' Kimi Raikonnen - third in the championship standings - was 10th.
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