Nico Rosberg led the way in Friday afternoon practice at Sakhir, as Mercedes-powered cars filled the top four in 2010's second official session.
The two works Mercedes entries were first and third with Rosberg and Michael Schumacher, while McLaren's Lewis Hamilton and Jenson Button surrounded them in second and fourth.
Rosberg hit the front after 20 minutes, and the only subsequent change at the top came when the German shaved a further tenth off his time a quarter of an hour later, getting down to 1m55.409sec. By then, the field had settled into a run of longer stints and the times remained relatively static.
Hamilton's best lap was 0.4sec slower than Rosberg's, and the 2008 World Champion reported severe tire wear after just a handful of hours on the harder rubber early on. Schumacher was half a second off his teammate's pace in third, and 0.2sec ahead of Button.
Red Bull's two teams both had difficult sessions. Sebastian Vettel was the best of the quartet in fifth, but had two trips over the run-off at the final corner, while his teammate Mark Webber was sidelined in the pits with a driveshaft problem after just five laps.
At Toro Rosso, Sebastien Buemi spent the entire afternoon in the pits while the team worked on a problem at the rear of his car, and his teammate Jaime Alguersuari only narrowly avoided reversing into the barriers when he ran wide over a curb in the new section of the circuit and spun back across the track.
Nico Hulkenberg got into the top six for Williams, ahead of Felipe Massa in the best of the Ferraris. His teammate Fernando Alonso was ninth behind Renault's Vitaly Petrov, whose car shed its headrest under braking on an early run, but later showed encouraging pace.
Pedro de la Rosa completed the top 10 for Sauber, followed by teammate Kamui Kobayashi and morning pacesetter Adrian Sutil (Force India).
This time it was Lotus that emerged as the fastest of the new teams, with Heikki Kovalainen and Jarno Trulli jumping ahead of Virgin right at the end of the session. The duo had carried heavy fuel for most of the afternoon, but then ran lighter for their final runs and got to within 5.5sec of the pace, and beat the Virgins by a second.
Bruno Senna got Hispania's F1 life under way in earnest and completed 17 laps, 12.5sec off the pace. But his session ended with a scare as his car lurched under braking for the first corner and slid off the road – with replays suggesting it had shed a wheel nut. Senna's teammate Karun Chandhok spent the day on the sidelines, with his car not ready to run yet, the Indian will not join the fray until final practice on Saturday.
Pos Driver Team Time Laps
1. Rosberg Mercedes 1:55.409 23
2. Hamilton McLaren-Mercedes 1:55.854 + 0.445 22
3. Schumacher Mercedes 1:55.903 + 0.494 23
4. Button McLaren-Mercedes 1:56.076 + 0.667 28
5. Vettel Red Bull-Renault 1:56.459 + 1.050 18
6. Hulkenberg Williams-Cosworth 1:56.501 + 1.092 26
7. Massa Ferrari 1:56.555 + 1.146 30
8. Petrov Renault 1:56.750 + 1.341 26
9. Alonso Ferrari 1:57.140 + 1.731 25
10. de la Rosa Sauber-Ferrari 1:57.255 + 1.846 24
11. Kobayashi Sauber-Ferrari 1:57.352 + 1.943 27
12. Sutil Force India-Mercedes 1:57.361 + 1.952 29
13. Barrichello Williams-Cosworth 1:57.452 + 2.043 21
14. Liuzzi Force India-Mercedes 1:57.833 + 2.424 29
15. Kubica Renault 1:58.155 + 2.746 29
16. Alguersuari Toro Rosso-Ferrari 1:59.799 + 4.390 31
17. Webber Red Bull-Renault 2:00.444 + 5.035 12
18. Kovalainen Lotus-Cosworth 2:00.873 + 5.464 23
19. Trulli Lotus-Cosworth 2:00.990 + 5.581 14
20. Glock Virgin-Cosworth 2:02.037 + 6.628 3
21. di Grassi Virgin-Cosworth 2:02.188 + 6.779 21
22. Senna HRT-Cosworth 2:06.968 + 11.559 17
23. Buemi Toro Rosso-Ferrari 1
24. Chandhok HRT-Cosworth
All Timing Unofficial