Jenson Button beat Lewis Hamilton by a scant 0.002 second in the final Formula 1 practice session of 2009 in Abu Dhabi.
The pair of British World Champions had been closely matched during Friday's sessions and resumed battle today, with Button sneaking ahead right at the end of the hour and earning his first fastest time in an official session since he took pole in Monaco five months ago.
McLaren driver Hamilton had been the man to beat for the majority of the session.
Toro Rosso's Sebastien Buemi had swapped first place with Hamilton's teammate Heikki Kovalainen early on, and then Button edged ahead of them with a very early soft tire run. But then Hamilton completely blew them away with a 1m41.270s lap – 1.1sec quicker than anyone else – on hard tires just before the halfway point.
He later shaved a further 0.2sec off that mark, and although Buemi briefly nosed back ahead, when Hamilton switched to soft tires he rapidly moved back in front with a 1m40.810s two minutes from the end.
That looked set to stand as the best time of the session, until Button – back on harder tires – stole the top spot with a 1m40.625s. Hamilton, still on his now-worn softs, improving to just 0.002sec behind, but Button was going faster still on his next lap before backing off and returning to the pits.
Rubens Barrichello jumped to third in the final seconds in the second Brawn, ahead of Buemi.
Nick Heidfeld completed the top five for BMW, despite earlier expressing his amazement at teammate Robert Kubica's pace. In the end, the Pole was three places further back, behind Kovalainen and Toyota's Jarno Trulli. Adrian Sutil and Kimi Raikkonen filled the final top ten places for Force India and Ferrari.
The session passed without major incident, bar a brush of the barrier by Force India's Tonio Liuzzi and two quick spins from Renault's Romain Grosjean. But while there were no accidents, Jaime Alguersuari was sidelined for the entire hour as his Toro Rosso team worked to fix a hydraulic problem.
Pos Driver Team Time Laps
1. Button Brawn GP-Mercedes (B) 1:40.625 21
2. Hamilton McLaren-Mercedes (B) 1:40.627 + 0.002 18
3. Barrichello Brawn GP-Mercedes (B) 1:40.907 + 0.282 20
4. Buemi Toro Rosso-Ferrari (B) 1:40.934 + 0.309 22
5. Heidfeld BMW Sauber (B) 1:41.241 + 0.616 18
6. Kovalainen McLaren-Mercedes (B) 1:41.263 + 0.638 20
7. Trulli Toyota (B) 1:41.310 + 0.685 23
8. Kubica BMW Sauber (B) 1:41.322 + 0.697 20
9. Sutil Force India-Mercedes (B) 1:41.372 + 0.747 22
10. Raikkonen Ferrari (B) 1:41.373 + 0.748 23
11. Vettel Red Bull-Renault (B) 1:41.403 + 0.778 19
12. Rosberg Williams-Toyota (B) 1:41.478 + 0.853 22
13. Kobayashi Toyota (B) 1:41.499 + 0.874 24
14. Liuzzi Force India-Mercedes (B) 1:41.675 + 1.050 20
15. Webber Red Bull-Renault (B) 1:41.682 + 1.057 15
16. Alonso Renault (B) 1:41.897 + 1.272 19
17. Nakajima Williams-Toyota (B) 1:42.156 + 1.531 21
18. Grosjean Renault (B) 1:42.213 + 1.588 19
19. Fisichella Ferrari (B) 1:42.351 + 1.726 23
All timing unofficial