Lewis Hamilton set the early pace in Friday's first practice for the Korean GP, outpacing Sebastian Vettel by 0.037s while Kimi Raikkonen crashed.
Marussia test driver Rodolfo Gonzalez was the only driver to set a time in the first 30 minutes and also the only one to crash his car.
With 24 minutes on the clock, he hit the inside barrier at Turn 13, sheering off the front wing and the tip of his Marussia's nose before spinning around and tagging the wall with the car's rear.
With Gonzalez back in the pits it was Sergio Perez's turn to control the timesheets as the McLaren driver lowered the benchmark lap after lap ahead of Force India tester James Calado and his own team-mate Jenson Button.
However, the big boys then came out to play.
Nico Rosberg and Fernando Alonso each had a brief stint at the front before Lewis Hamilton overhauled them with a 1:39.630 while the Red Bull drivers came into play with Mark Webber up to second ahead of Rosberg and Sebastian Vettel.
As the clock counted down, Jenson Button broke the Mercedes - Red Bull lock out to go fourth only to fall back out as Vettel climbed to second in the final minute of the session, 0.037s behind Hamilton.
Button therefore finished fifth ahead of Alonso, Romain Grosjean and the crashing Kimi Raikkonen, whose practice session ended in the barriers with serious damage to the front and rear of his E21.
Perez and Felipe Massa, who had an issue with his tyres, completed the top ten.
1 Lewis Hamilton Mercedes 1:39.630 20 laps
2 Sebastian Vettel Red Bull 1:39.667 +0.037 20 laps
3 Mark Webber Red Bull 1:39.816 +0.186 19 laps
4 Nico Rosberg Mercedes 1:40.117 +0.487 20 laps
5 Jenson Button McLaren 1:40.215 +0.585 22 laps
6 Fernando Alonso Ferrari 1:40.374 +0.744 18 laps
7 Romain Grosjean Lotus 1:40.396 +0.766 19 laps
8 Kimi Raikkonen Lotus 1:40.677 +1.047 15 laps
9 Sergio Perez McLaren 1:40.860 +1.230 20 laps
10 Felipe Massa Ferrari 1:40.880 +1.250 13 laps
11 Nico Hulkenberg Sauber 1:40.899 +1.269 20 laps
12 Adrian Sutil Force India 1:41.432 +1.802 18 laps
13 Pastor Maldonado Williams :41.482 +1.852 22 laps
14 Esteban Gutierrez Sauber 1:41.626 +1.996 21 laps
15 Jean-Eric Vergne Toro Rosso 1:41.924 +2.294 19 laps
16 Valtteri Bottas Williams 1:42.002 +2.372 20 laps
17 Daniel Ricciardo Toro Rosso 1:42.043 +2.413 18 laps
18 James Calado Force India 1:43.008 +3.378 21 laps
19 Charles Pic Caterham 1:43.660 +4.030 20 laps
20 Giedo van der Garde Caterham 1:43.883 +4.253 19 laps
21 Max Chilton Marussia 1:44.100 +4.470 14 laps
22 Rodolfo Gonzalez Marussia 1:46.810 +7.180 10 laps
Friday's Pictures From Korea
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