Mark Webber kept Red Bull ahead in final Japanese Grand Prix practice at Suzuka, as his team-mate Sebastian Vettel ran into mechanical problems.
It was a commanding morning for Webber, who put himself on top during the early part of the session when everyone was on hard tyres.
He was deposed by an early medium-tyre run from Lotus's Romain Grosjean, but once Webber was on the softer rubber as well, he burst clear with a 1m32.053s, 0.643s in front of the field.
Vettel had been second to Webber on hard tyres, 0.314s off his team-mate's pace after what he admitted had been a scruffy lap.
That ended up being Vettel's best run as a KERS problem then left him watching the final quarter of an hour from the pits.
Webber looked set to keep his six-tenth advantage until late runs from the two Mercedes.
First Nico Rosberg got to within 0.302s of the Red Bull, then Lewis Hamilton put in a 1m32.187s after the flag to take second from his team-mate, 0.134s behind Webber.
Grosjean was pushed back to fourth, ahead of Ferrari duo Fernando Alonso and Felipe Massa.
Jenson Button took an encouraging seventh place for McLaren, within a tenth of the Ferraris.
Kimi Raikkonen, Vettel and Nico Hulkenberg completed the top 10.
Adrian Sutil provided the only crash of the session when he ran wide on the exit of Spoon and put his Force India into the barriers, sustaining relatively minor damage.
Pos Driver Team/Car Time Gap Laps 1. Mark Webber Red Bull-Renault 1m32.053s 17 2. Lewis Hamilton Mercedes 1m32.187s +0.134s 18 3. Nico Rosberg Mercedes 1m32.355s +0.302s 18 4. Romain Grosjean Lotus-Renault 1m32.707s +0.654s 26 5. Fernando Alonso Ferrari 1m32.800s +0.747s 14 6. Felipe Massa Ferrari 1m32.815s +0.762s 14 7. Jenson Button McLaren-Mercedes 1m32.869s +0.816s 17 8. Kimi Raikkonen Lotus-Renault 1m32.946s +0.893s 25 9. Sebastian Vettel Red Bull-Renault 1m33.036s +0.983s 8 10. Nico Hulkenberg Sauber-Ferrari 1m33.076s +1.023s 12 11. Sergio Perez McLaren-Mercedes 1m33.158s +1.105s 15 12. Jean-Eric Vergne Toro Rosso-Ferrari 1m33.260s +1.207s 15 13. Daniel Ricciardo Toro Rosso-Ferrari 1m33.490s +1.437s 16 14. Pastor Maldonado Williams-Renault 1m33.638s +1.585s 17 15. Paul di Resta Force India-Mercedes 1m33.660s +1.607s 19 16. Esteban Gutierrez Sauber-Ferrari 1m33.732s +1.679s 15 17. Valtteri Bottas Williams-Renault 1m33.955s +1.902s 18 18. Adrian Sutil Force India-Mercedes 1m34.773s +2.720s 8 19. Giedo van der Garde Caterham-Renault 1m35.473s +3.420s 20 20. Charles Pic Caterham-Renault 1m35.518s +3.465s 18 21. Max Chilton Marussia-Cosworth 1m35.844s +3.791s 16 22. Jules Bianchi Marussia-Cosworth 1m39.378s +7.325s 20