Nico Rosberg was quickest in first practice for the 2014 Formula 1 British Grand Prix at Silverstone, 0.731s faster than Mercedes team-mate Lewis Hamilton.
The session was red-flagged for 16 minutes after Felipe Massa crashed his Williams at Stowe, and track activity resumed with 47 minutes remaining.
Both Rosberg and Hamilton set their quickest times on the medium-compound Pirellis early in the session before completing the balance of their running on the harder of the available compounds.
Hamilton did look as though he might overhaul his team-mate at one point, going fastest of all in the first sector, but he had to back off because Marcus Ericsson spun at Becketts, bringing out the yellow flags.
Fernando Alonso was best of the rest for Ferrari, 0.839s off Rosberg's quickest with a lap set right at the end of the session following a rear-wing change.
Red Bull's Daniel Ricciardo was fourth quickest but had to cut his session short after reporting gearbox problems. He was three tenths faster than team-mate Sebastian Vettel.
Vettel put in all but one of his laps after the session resumed following the red flag.
Jenson Button was fastest of the two McLarens, who were split by the Toro Rossos of Daniil Kvyat and Jean-Eric Vergne.
Caterham's Marcus Ericsson was the slowest of the drivers to complete a meaningful number of laps, a second off the pace of Max Chilton's Marussia.
Both Marussia drivers reported understeer as well as oversteer, and Chilton observed that he had more oversteer than Jules Bianchi in high-speed corners.
Williams, frontrunner in Austria two weeks ago, was unable to show its hand or even run through its normal FP1 programme.
Susie Wolff's much-anticipated appearance came to a frustratingly early halt when an internal component failure caused her engine to shut down after completing just four laps.
Massa ran wide on the exit of Stowe after seven laps and spun back over the track, making a heavy impact with the inside wall.
Technical problems also confined Caterham's Robin Frijns and the Lotus of Pastor Maldonado to the garage early in the session, though Frijns was able to take to the track with 10 minutes remaining.
Pos Driver Team Time Gap Laps
1. Nico Rosberg Mercedes 1m35.424s 25
2. Lewis Hamilton Mercedes 1m36.155s +0.731s 22
3. Fernando Alonso Ferrari 1m36.263s +0.839s 23
4. Daniel Ricciardo Red Bull-Renault 1m36.623s +1.199s 21
5. Kimi Raikkonen Ferrari 1m36.703s +1.279s 23
6. Sebastian Vettel Red Bull-Renault 1m36.921s +1.497s 20
7. Jenson Button McLaren-Mercedes 1m36.963s +1.539s 25
8. Daniil Kvyat Toro Rosso-Renault 1m37.175s +1.751s 29
9. Jean-Eric Vergne Toro Rosso-Renault 1m37.227s +1.803s 25
10. Kevin Magnussen McLaren-Mercedes 1m37.231s +1.807s 30
11. Sergio Perez Force India-Mercedes 1m37.720s +2.296s 22
12. Romain Grosjean Lotus-Renault 1m37.910s +2.486s 21
13. Esteban Gutierrez Sauber-Ferrari 1m38.056s +2.632s 18
14. Daniel Juncadella Force India-Mercedes 1m38.083s +2.659s 23
15. Giedo van der Garde Sauber-Ferrari 1m38.328s +2.904s 19
16. Jules Bianchi Marussia-Ferrari 1m38.917s +3.493s 12
17. Felipe Massa Williams-Mercedes 1m39.461s +4.037s 7
18. Max Chilton Marussia-Ferrari 1m39.814s +4.390s 24
19. Marcus Ericsson Caterham-Renault 1m40.597s +5.173s 19
20. Robin Frijns Caterham-Renault 1m42.261s +6.837s 11
21. Susie Wolff Williams-Mercedes 1m44.212s +8.788s 4
22. Pastor Maldonado Lotus-Renault no time 2