Jenson Button snatched the upper hand in the battle between Britain's two Formula One world champions after going head-to-head with predecessor Lewis Hamilton in the final Saturday practice session of the 2009 season.
Amid the space-age surroundings of the new Yas Marina circuit, the pair traded times throughout the hour-long session, before Button eventually snatched top spot by a scant 0.002secs, as his final lap proved enough to end Hamilton's reign at the top of the timesheets. The Brawn GP driver also posted the fastest lap of the weekend, lowering Friday's benchmark by over half a second, to 1min 40.625secs.
Rubens Barrichello underlined the fact that Brawn could be a contender for victory - even if McLaren's KERS system could prove to be the deciding factor - by claiming third spot a couple of tenths back, while Sebastien Buemi and Nick Heidfeld rounded out the top five. The Swiss driver had led early on but could not prevent the Britons from moving to the front, although he ensured that Toro Rosso could be a dark horse this weekend.
Heidfeld bounced back from a spot of mid-session head-scratching, when he trailed BMW Sauber team-mate Robert Kubica by a dispiriting margin, to claim fifth, albeit still six-tenths off Button's mark, but ended up ahead of Friday pacesetter Heikki Kovalainen. Jarno Trulli, Kubica, Adrian Sutil and Kimi Raikkonen completed a varied top ten.
The dusty surface continued to keep the drivers occupied, with several still exploring the levels of grip while trying to raise their pace, but again there were no serious incidents, although Tonio Liuzzi tested the strength of his Force India by bouncing off one of the closer walls.
At the bottom of the list, Jaime Alguersuari failed to complete a lap after his Toro Rosso ran into a hydraulic problem, and will suffer when the qualifying hour comes around this evening.