Lewis Hamilton and Nico Rosberg gave Mercedes the early advantage in Japanese Grand Prix Friday practice.
In a 'two by two' top eight in which the driver pairings from Formula 1's leading four teams lined up next to each other, Mercedes secured a one-two ahead of the Red Bulls.
Rosberg put in his quick lap, a 1m34.487s, first but it was usurped shortly afterwards when Hamilton went 0.330 seconds quicker.
Sebastian Vettel was the fastest Red Bull in third, albeit 0.611s off the pace.
His team-mate Mark Webber took fourth, followed by the Ferraris, and Lotuses, with Felipe Massa and Romain Grosjean outpacing their respective team-mates.
The symmetry was broken at the foot of the top 10, where Daniel Ricciardo put his Toro Rosso between the McLarens of Sergio Perez and Jenson Button late on.
Several drivers further down the order ran into trouble. Pastor Maldonado had to park his Williams at Spoon after spinning when his left rear wheel flew off.
Both Jules Bianchi and Giedo van der Garde crashed at Degner. While the Caterham only just nudged the tyres, Bianchi's Marussia will need a more substantial rebuild following his early crash.
Despite only managing eight laps on his Suzuka debut, Bianchi was a second clear of Marussia team-mate Max Chilton and was only narrowly pipped to rear quartet honours by Caterham's returnee practice driver Heikki Kovalainen.
Pos Driver Team Time Gap Laps 1. Lewis Hamilton Mercedes 1m34.157s 19 2. Nico Rosberg Mercedes 1m34.487s +0.330s 19 3. Sebastian Vettel Red Bull-Renault 1m34.768s +0.611s 24 4. Mark Webber Red Bull-Renault 1m34.787s +0.630s 20 5. Felipe Massa Ferrari 1m35.126s +0.969s 14 6. Fernando Alonso Ferrari 1m35.154s +0.997s 16 7. Romain Grosjean Lotus-Renault 1m35.179s +1.022s 15 8. Kimi Raikkonen Lotus-Renault 1m35.364s +1.207s 17 9. Sergio Perez McLaren-Mercedes 1m35.450s +1.293s 27 10. Daniel Ricciardo Toro Rosso-Ferrari 1m35.635s +1.478s 19 11. Jenson Button McLaren-Mercedes 1m35.868s +1.711s 22 12. Nico Hülkenberg Sauber-Ferrari 1m35.900s +1.743s 18 13. Jean-Eric Vergne Toro Rosso-Ferrari 1m36.066s +1.909s 20 14. Adrian Sutil Force India-Mercedes 1m36.165s +2.008s 19 15. Pastor Maldonado Williams-Renault 1m36.178s +2.021s 12 16. Valtteri Bottas Williams-Renault 1m36.340s +2.183s 23 17. Paul Di Resta Force India-Mercedes 1m36.399s +2.242s 18 18. Esteban Gutierrez Sauber-Ferrari 1m36.760s +2.603s 22 19. Heikki Kovalainen Caterham-Renault 1m37.595s +3.438s 22 20. Jules Bianchi Marussia-Cosworth 1m37.629s +3.472s 8 21. Giedo van der Garde Caterham-Renault 1m38.025s +3.868s 15 22. Max Chilton Marussia-Cosworth 1m38.763s +4.606s 18