Mercedes underlined its dominant position at the front of Formula 1 by comfortably leading the way in the first free practice session for the Hungarian Grand Prix.
Lewis Hamilton beat team-mate Nico Rosberg to the fastest time by just 0.183 seconds, after struggling with his brakes in the early part of the session.
The silver cars were the only ones to lap below 1m26s around the Hungaroring.
Kimi Raikkonen finished up best of the rest in third, six tenths of a second adrift of championship leader Rosberg.
The Finn matched Hamilton in the first sector but his Ferrari fell away across the rest of the circuit.
Raikkonen lapped four tenths clear of Ferrari team-mate Fernando Alonso, who was in turn four tenths faster than reigning world champion Sebastian Vettel in the best of the Red Bulls.
Kevin Magnussen's McLaren rounded out the top six, ahead of Jean-Eric Vergne's Toro Rosso, the second Red Bull of Daniel Ricciardo, and the sister McLaren of Jenson Button.
Felipe Massa was fastest of the two Williams drivers in 10th, while team-mate Valtteri Bottas was only 15th, behind Esteban Gutierrez in the best of the Saubers, Nico Hulkenberg's Force India, Daniil Kvyat's Toro Rosso, and Pastor Maldonado in the best of the Lotus.
Hulkenberg's Force India team-mate Sergio Perez was next, ahead of the troublesome second Lotus of Romain Grosjean, which stopped early with a technical issue related to the car's water system.
Adrian Sutil was 18th fastest, more than a second slower than Sauber team-mate Gutierrez, but well ahead of the two Caterhams - led by Kamui Kobayashi - and the two Marussias.
There were a number of brake lock-ups and trips across the circuit run-off areas as drivers explored the track's limits early on, but the most dramatic moment of the session befell Max Chilton as he returned to the pits after his installation lap.
Chilton is hoping his form will improve this weekend, after switching back to a chassis he used before June's Austrian GP, but the Briton's session was barely five minutes old when his Marussia caught fire in the pitlane when some oil leaked onto the car's exhaust, requiring a change of gearbox on the MR03.
He returned to the track just in time to register a flying lap two tenths clear of his team-mate Bianchi.
Pos Driver Team Time Gap Laps
1. Lewis Hamilton Mercedes 1m25.814s 27
2. Nico Rosberg Mercedes 1m25.997s +0.183s 31
3. Kimi Raikkonen Ferrari 1m26.421s +0.607s 29
4. Fernando Alonso Ferrari 1m26.872s +1.058s 23
5. Sebastian Vettel Red Bull-Renault 1m27.220s +1.406s 28
6. Kevin Magnussen McLaren-Mercedes 1m27.357s +1.543s 28
7. Jean-Eric Vergne Toro Rosso-Renault 1m27.683s +1.869s 30
8. Daniel Ricciardo Red Bull-Renault 1m27.782s +1.968s 16
9. Jenson Button McLaren-Mercedes 1m27.804s +1.990s 27
10. Felipe Massa Williams-Mercedes 1m27.960s +2.146s 24
11. Esteban Gutierrez Sauber-Ferrari 1m27.967s +2.153s 25
12. Nico Hulkenberg Force India-Mercedes 1m28.101s +2.287s 28
13. Daniil Kvyat Toro Rosso-Renault 1m28.208s +2.394s 32
14. Pastor Maldonado Lotus-Renault 1m28.266s +2.452s 28
15. Valtteri Bottas Williams-Mercedes 1m28.330s +2.516s 21
16. Sergio Perez Force India-Mercedes 1m28.376s +2.562s 24
17. Romain Grosjean Lotus-Renault 1m28.593s +2.779s 24
18. Adrian Sutil Sauber-Ferrari 1m29.025s +3.211s 23
19. Kamui Kobayashi Caterham-Renault 1m30.363s +4.549s 30
20. Marcus Ericsson Caterham-Renault 1m30.892s +5.078s 24
21. Max Chilton Marussia-Ferrari 1m31.004s +5.190s 5
22. Jules Bianchi Marussia-Ferrari 1m31.248s +5.434s 20