Webber fastest, Vettel slowed by KERS
Red Bull's Mark Webber was fastest in Saturday's final practice for the Japanese Grand Prix after world champion teammate Sebastian Vettel was sidelined by a KERS battery problem.
Vettel, who can secure his fourth successive Formula One title in Sunday's race if he wins and Ferrari's Fernando Alonso fails to finish in the top eight, ended the session with the ninth quickest time.
However the 26-year-old German, who has qualified on pole position in Japan for the past four years and has also won three of the last four races at Suzuka, managed only eight laps compared to Webber's 17.
Vettel was changed into a jeans and T-shirt before the end of the session, watching in the garage for the final 15 minutes as mechanics changed the battery on his car's KERS energy recovery system.
Webber's time of one minute 32.053 seconds was 0.134 faster than Lewis Hamilton in the Mercedes with the Briton's teammate Nico Rosberg third fastest.
Alonso, who is second overall in the title race but 77 points adrift of Vettel, was fifth fastest with the main battle in qualifying looking likely to be between Red Bull and Mercedes.
Adrian Sutil crashed his Force India at the exit to the Spoon Curve, spinning and hitting the barriers.
1. Mark Webber (Australia) RedBull - Renault 1:32.053
2. Lewis Hamilton (Britain) Mercedes 1:32.187
3. Nico Rosberg (Germany) Mercedes 1:32.355
4. Romain Grosjean (France) Lotus - Renault 1:32.707
5. Fernando Alonso (Spain) Ferrari 1:32.800
6. Felipe Massa (Brazil) Ferrari 1:32.815
7. Jenson Button (Britain) McLaren 1:32.869
8. Kimi Raikkonen (Finland) Lotus - Renault 1:32.946
9. Sebastian Vettel (Germany) RedBull - Renault 1:33.036
10. Nico Huelkenberg (Germany) Sauber - Ferrari 1:33.076
11. Sergio Perez (Mexico) McLaren 1:33.158
12. Jean-Eric Vergne (France) Toro Rosso - Ferrari 1:33.260
13. Daniel Ricciardo (Australia) Toro Rosso - Ferrari 1:33.490
14. Pastor Maldonado (Venezuela) Williams - Renault 1:33.638
15. Paul Di Resta (Britain) Force India - Mercedes 1:33.660
16. Esteban Gutierrez (Mexico) Sauber - Ferrari 1:33.732
17. Valtteri Bottas (Finland) Williams - Renault 1:33.955
18. Adrian Sutil (Germany) Force India - Mercedes 1:34.773
19. Giedo van der Garde (Netherlands) Caterham - Renault 1:35.473
20. Charles Pic (France) Caterham - Renault 1:35.518
21. Max Chilton (Britain) Marussia - Cosworth 1:35.844
22. Jules Bianchi (France) Marussia - Cosworth 1:39.378