Former world champion Michael Schumacher set the early pace at a wet opening practice in Korea.
Mercedes ace holds off Vettel's challenge
Former world champion Michael Schumacher set the early pace at a wet opening practice in Korea - although six drivers opted against venturing out.
Those who did take to the track on Friday kept their involvement to a minimum, with better conditions expected for the rest of the weekend.
Schumacher, though, proved to be the quickest in the wet at the Yeongam circuit, clocking a 2:02.784 to finish 0.068s ahead of newly-crowned world champion Sebastian Vettel.
Scotland's Paul di Resta was third in his Force India in 2:02.912, ahead of Adrian Sutil, Sebastien Buemi and Kamui Kobayashi.
McLaren's Lewis Hamilton recorded the seventh fastest time of the session, with team-mate Jenson Button among those who remained in the garage.
Ferrari duo Fernando Alonso and Felipe Massa, Vitaly Petrov, Heikki Kovalainen and Bruno Senna also opted to wait until an improvement in the weather.
Practice One: 1 Michael Schumacher (Ger) Mercedes GP 2:02.784, 2 Sebastian Vettel (Ger) Red Bull 2:02.840, 3 Paul di Resta (Gbr) Force India 2:02.912, 4 Adrian Sutil (Ger) Force India 2:03.141, 5 Sebastien Buemi (Sui) Toro Rosso 2:03.182, 6 Kamui Kobayashi (Jpn) Sauber 2:03.292, 7 Lewis Hamilton (Gbr) McLaren 2:03.391, 8 Nico Rosberg (Ger) Mercedes GP 2:04.311, 9 Sergio Perez (Mex) Sauber 2:04.797, 10 Mark Webber (Aus) Red Bull 2:05.183, 11 Karun Chandhok (Ind) Lotus 2:06.350, 12 Pastor Maldonado (Ven) Williams F1 2:06.852, 13 Jean-Eric Vergne (Fra) Toro Rosso 2:07.541, 14 Rubens Barrichello (Bra) Williams F1 2:08.218, 15 Narain Karthikeyan (Ind) Hispania 2:08.832, 16 Daniel Ricciardo (Aus) Hispania 2:09.232, 17 Jerome d'Ambrosio (Bel) Virgin Racing 2:12.658, 18 Timo Glock (Ger) Virgin Racing 2:14.508, 19 Jenson Button (Gbr) McLaren, 20 Vitaly Petrov (Rus) Lotus-Renault, 21 Heikki Kovalainen (Fin) Lotus, 22 Bruno Senna (Bra) Lotus-Renault, 23 Fernando Alonso (Spn) Ferrari, 24 Felipe Massa (Bra) Ferrari
