Mercedes’ Lewis Hamilton had the edge over the Red Bull pairing of Sebastian Vettel and Mark Webber as practice got under way in Korea on Friday.
The Briton lapped in 1m 39.630s which proved quick enough to withstand a very late challenge from Sebastian Vettel, as the world champion pared down to 1m 39.667s to miss out by 0.037s. Mark Webber underlined the Red Bull threat with the third fastest time of 1m 39.816s.
Nico Rosberg ended the morning in fourth place in the second Mercedes on 1m 40.117s, ahead of late-improving Jenson Button on 1m 40.215s for McLaren and Fernando Alonso on 1m 40.374s for Ferrari.
| Pos. | Drivers | Teams | Time | Laps |
| 01. |  Lewis Hamilton |
Mercedes AMG Petronas | 1:39.630 | 20 |
| 02. |  Sebastian Vettel |
Red Bull Racing | 1:39.667 | 20 |
| 03. |  Mark Webber |
Red Bull Racing | 1:39.816 | 19 |
| 04. | Nico Rosberg |
Mercedes AMG Petronas | 1:40.117 | 20 |
| 05. | Jenson Button |
Vodafone McLaren Mercedes | 1:40.215 | 22 |
| 06. |  Fernando Alonso |
Scuderia Ferrari | 1:40.374 | 18 |
| 07. |  Romain Grosjean |
Lotus F1 | 1:40.396 | 19 |
| 08. |  Kimi Raikkonen |
Lotus F1 | 1:40.677 | 15 |
| 09. |  Sergio Perez |
Vodafone McLaren Mercedes | 1:40.860 | 20 |
| 10. |  Felipe Massa |
Scuderia Ferrari | 1:40.880 | 13 |
| 11. | Nico Hulkenberg |
Sauber F1 | 1:40.899 | 20 |
| 12. | Adrian Sutil |
Sahara Force India | 1:41.432 | 18 |
| 13. |  Pastor Maldonado |
Williams F1 | 1:41.482 | 22 |
| 14. | Esteban Gutiérrez |
Sauber F1 | 1:41.626 | 21 |
| 15. | Jean-Eric Vergne |
Scuderia Toro Rosso | 1:41.924 | 19 |
| 16. | Valtteri Bottas |
Williams F1 | 1:42.002 | 20 |
| 17. | Daniel Ricciardo |
Scuderia Toro Rosso | 1:42.043 | 18 |
| 18. | James Calado |
Sahara Force India | 1:43.008 | 21 |
| 19. | Charles Pic |
Caterham F1 Team | 1:43.660 | 20 |
| 20. |  Giedo van der Garde |
Caterham F1 Team | 1:43.883 | 19 |
| 21. | Max Chilton |
Marussia F1 | 1:44.100 | 14 |
| 22. | Rodolfo Gonzales |
Marussia F1 | 1:46.810 | 10 |
