Heikki Kovalainen and Lewis Hamilton gave McLaren a one-two in second practice for the inaugural Abu Dhabi Grand Prix.
Going into the closing moments it looked like Hamilton and newly crowned World Champion Jenson Button (Brawn) would repeat their first and second places from the morning, before Kovalainen edged ahead of his teammate with a late soft tire run.
At the start of the session Hamilton had an early trip over the run-off area at the end of the long back straight before establishing himself in front following a quick exchange with Kovalainen.
Sebastien Buemi then repeated the strong practice form he had showed in both Japan and Brazil by producing an ever-faster series of laps that took him up to first and then increasingly further away from the pack. His advantage eventually reached nearly 0.8sec, before others made gains and Hamilton reclaimed the top spot 36 minutes in.
That was where he stayed, as Button and Red Bull's Sebastian Vettel closed to within a few fractions of a second, until Kovalainen put softs on and improved to 1m41.307s.
Behind Button and Vettel, Toyota's rookie Kamui Kobayashi impressed greatly with fifth place, having been among the frontrunners for most of the evening. Buemi fell to sixth, ahead of Mark Webber and Rubens Barrichello in the second Red Bull and Brawn respectively.
Adrian Sutil's brake problems continued, with the German pitting his Force India following a major lock-up at the end of the long straight. He later rejoined to take 11th.
Robert Kubica was consigned to the bottom of the timesheets when his BMW Sauber suffered an apparent engine failure on the exit of the first chicane after just 13 laps.
The session gave a preview of the lighting conditions the drivers will experience in Sunday's race, which also starts at 5 p.m. local time. Practice began at dusk, but darkness soon descended on Yas Marina, leaving the circuit's floodlights to illuminate the majority of the session.
Pos Driver Team Time Laps
1. Kovalainen McLaren-Mercedes (B) 1:41.307 35
2. Hamilton McLaren-Mercedes (B) 1:41.504 + 0.197 34
3. Button Brawn-Mercedes (B) 1:41.541 + 0.234 39
4. Vettel Red Bull-Renault (B) 1:41.591 + 0.284 37
5. Kobayashi Toyota (B) 1:41.636 + 0.329 34
6. Buemi Toro Rosso-Ferrari (B) 1:41.683 + 0.376 37
7. Webber Red Bull-Renault (B) 1:41.684 + 0.377 34
8. Barrichello Brawn-Mercedes (B) 1:41.831 + 0.524 38
9. Rosberg Williams-Toyota (B) 1:41.931 + 0.624 39
10. Raikkonen Ferrari (B) 1:41.987 + 0.680 39
11. Sutil Force India-Mercedes (B) 1:42.180 + 0.873 28
12. Nakajima Williams-Toyota (B) 1:42.245 + 0.938 36
13. Heidfeld BMW-Sauber (B) 1:42.278 + 0.971 36
14. Trulli Toyota (B) 1:42.409 + 1.102 30
15. Liuzzi Force India-Mercedes (B) 1:42.530 + 1.223 33
16. Alonso Renault (B) 1:42.782 + 1.475 29
17. Fisichella Ferrari (B) 1:42.932 + 1.625 37
18. Grosjean Renault (B) 1:43.021 + 1.714 37
19. Alguersuari Toro Rosso-Ferrari (B) 1:43.022 + 1.715 39
20. Kubica BMW-Sauber (B) 1:43.708 + 2.401 13
All Timing Unofficial