The pendulum seems to be swinging towards the Red Bull corner with Vettel looking quick again on day 1 of the Korean Grand Prix:

Quote Originally Posted by Practice 1
Pos Driver Car Time Gap Laps
1. Lewis Hamilton McLaren-Mercedes 1m39.148s 23
2. Fernando Alonso Ferrari 1m39.450s + 0.302s 21
3. Mark Webber Red Bull-Renault 1m39.575s + 0.427s 21
4. Felipe Massa Ferrari 1m39.854s + 0.706s 23
5. Sebastian Vettel Red Bull-Renault 1m40.088s + 0.940s 21
6. Michael Schumacher Mercedes 1m40.221s + 1.073s 21
7. Nico Rosberg Mercedes 1m40.396s + 1.248s 24
8. Romain Grosjean Lotus-Renault 1m40.422s + 1.274s 22
9. Paul di Resta Force India-Mercedes 1m40.440s + 1.292s 19
10. Jenson Button McLaren-Mercedes 1m40.480s + 1.332s 21
11. Kimi Raikkonen Lotus-Renault 1m40.929s + 1.781s 14
12. Pastor Maldonado Williams-Renault 1m41.048s + 1.900s 25
13. Jules Bianchi Force India-Mercedes 1m41.140s + 1.992s 21
14. Kamui Kobayashi Sauber-Ferrari 1m41.220s + 2.072s 19
15. Sergio Perez Sauber-Ferrari 1m41.514s + 2.366s 20
16. Daniel Ricciardo Toro Rosso-Ferrari 1m41.596s + 2.448s 23
17. Jean-Eric Vergne Toro Rosso-Ferrari 1m42.021s + 2.873s 25
18. Valtteri Bottas Williams-Renault 1m42.027s + 2.879s 23
19. Heikki Kovalainen Caterham-Renault 1m42.104s + 2.956s 24
20. Timo Glock Marussia-Cosworth 1m42.175s + 3.027s 13
21. Charles Pic Marussia-Cosworth 1m42.706s + 3.558s 22
22. Giedo van der Garde Caterham-Renault 1m42.820s + 3.672s 19
23. Pedro de la Rosa HRT-Cosworth 1m44.517s + 5.369s 23
24. Dani Clos HRT-Cosworth 1m45.735s + 6.587s 22

Korean GP: Lewis Hamilton sets practice one pace for McLaren - F1 news - AUTOSPORT.com
Quote Originally Posted by Practice 2
Pos Driver Car Time Gap Laps
1. Sebastian Vettel Red Bull-Renault 1m38.832s 33
2. Mark Webber Red Bull-Renault 1m38.864s + 0.032 33
3. Fernando Alonso Ferrari 1m39.160s + 0.328 28
4. Jenson Button McLaren-Mercedes 1m39.219s + 0.387 29
5. Michael Schumacher Mercedes 1m39.330s + 0.498 31
6. Felipe Massa Ferrari 1m39.422s + 0.590 30
7. Nico Rosberg Mercedes 1m39.584s + 0.752 36
8. Lewis Hamilton McLaren-Mercedes 1m39.717s + 0.885 25
9. Nico Hulkenberg Force India-Mercedes 1m39.739s + 0.907 33
10. Kimi Raikkonen Lotus-Renault 1m39.839s + 1.007 26
11. Romain Grosjean Lotus-Renault 1m39.957s + 1.125 28
12. Bruno Senna Williams-Renault 1m40.089s + 1.257 32
13. Paul di Resta Force India-Mercedes 1m40.112s + 1.280 34
14. Kamui Kobayashi Sauber-Ferrari 1m40.445s + 1.613 28
15. Sergio Perez Sauber-Ferrari 1m40.745s + 1.913 11
16. Jean-Eric Vergne Toro Rosso-Ferrari 1m40.789s + 1.957 31
17. Daniel Ricciardo Toro Rosso-Ferrari 1m40.997s + 2.165 32
18. Pastor Maldonado Williams-Renault 1m41.200s + 2.368 33
19. Heikki Kovalainen Caterham-Renault 1m41.602s + 2.770 23
20. Timo Glock Marussia-Cosworth 1m42.596s + 3.764 28
21. Charles Pic Marussia-Cosworth 1m43.066s + 4.234 21
22. Vitaly Petrov Caterham-Renault 1m43.067s + 4.235 22
23. Narain Karthikeyan HRT-Cosworth 1m43.869s + 5.037 36
24. Pedro de la Rosa HRT-Cosworth 1m44.533s + 5.701 24

Korean Grand Prix: Sebastian Vettel sets pace in second practice - F1 news - AUTOSPORT.com