Sebastian Vettel set the fastest time of Friday's first practice session in Abu Dhabi.
The Yas Marina track was damp at the beginning, following a surprise downpour this morning.
Friday's first practice is usually an exercise in circuit cleaning and that was the case even more today thanks to the patches of damp, particulary in the shade of the unique circuit's bridges and trackside buildings.
Both McLaren and Red Bull spent time early on testing parts on their cars, with both having brought upgraded rear wings to the season finale. Mark Webber particularly spent laps early on assessing the wing with flow-vis paint on his RB6.
Everyone posted at least installation laps but few returned for much meaningful running until the last half hour - Lewis Hamilton, for example did not complete a timed lap until there were just 18 minutes left on the clock.
When the times did fall into the 1m43s, it was the Red Bulls of Webber and Vettel, and Hamilton's McLaren that set the pace.
All 24 cars were on the circuit at the end of the 90-minute session, by which time the circuit was in good enough condition for Vettel to break into the 1m42s.
That left him six tenths clear of Hamilton, with Jenson Button jumping up to third late on in the second McLaren. Webber finished up fourth, ahead of Robert Kubica's Renault and Fernando Alonso's Ferrari.
Michael Schumacher, Kamui Kobayashi, Nico Rosberg and Nick Heidfeld completed the top 10.
The session passed without any major incidents. Several cars had trips off the damp track early on, but Fairuz Fauzy (Lotus) was the only one to spin. Rubens Barrichello's Williams stopped on his way back to the pits after the chequered flag.
Pos Driver Car Time Gap Laps 1. Sebastian Vettel Red Bull-Renault 1m42.760s 18 2. Lewis Hamilton McLaren-Mercedes 1m43.369s + 0.609s 16 3. Jenson Button McLaren-Mercedes 1m43.785s + 1.025s 19 4. Mark Webber Red Bull-Renault 1m43.840s + 1.080s 19 5. Robert Kubica Renault 1m44.080s + 1.320s 19 6. Fernando Alonso Ferrari 1m44.121s + 1.361s 17 7. Michael Schumacher Mercedes 1m44.199s + 1.439s 19 8. Kamui Kobayashi Sauber-Ferrari 1m44.604s + 1.844s 18 9. Nico Rosberg Mercedes 1m44.718s + 1.958s 19 10. Nick Heidfeld Sauber-Ferrari 1m44.737s + 1.977s 19 11. Felipe Massa Ferrari 1m45.160s + 2.400s 18 12. Vitaly Petrov Renault 1m45.445s + 2.685s 21 13. Rubens Barrichello Williams-Cosworth 1m45.474s + 2.714s 15 14. Adrian Sutil Force India-Mercedes 1m45.552s + 2.792s 20 15. Tonio Liuzzi Force India-Mercedes 1m45.585s + 2.825s 14 16. Jaime Alguersuari Toro Rosso-Ferrari 1m46.003s + 3.243s 20 17. Nico Hulkenberg Williams-Cosworth 1m46.644s + 3.884s 19 18. Sebastien Buemi Toro Rosso-Ferrari 1m47.105s + 4.345s 22 19. Timo Glock Virgin-Cosworth 1m48.450s + 5.690s 19 20. Jarno Trulli Lotus-Cosworth 1m48.472s + 5.712s 17 21. Lucas di Grassi Virgin-Cosworth 1m49.375s + 6.615s 13 22. Bruno Senna Hispania-Cosworth 1m49.590s + 6.830s 18 23. Christian Klien Hispania-Cosworth 1m50.274s + 7.514s 17 24. Fairuz Fauzy Lotus-Cosworth 1m51.705s + 8.945s 18 All timing unofficial