ABU DHABI - Nico Rosberg posted the fasted time ahead of teammate Lewis Hamilton in the third and final free practice Saturday for the title-deciding Abu Dhabi Grand Prix.
It was the first time in three attempts that Rosberg had beaten his Mercedes partner in practice. The 29-year-old German responded to Hamilton's domination of both practice sessions on Friday with a best lap of one minute and 41.424 seconds, edging 0.369sec clear of the title favourite.
Hamilton leads Rosberg by 17 points going into Sunday's race when the normal points will count double.
Rosberg must win, with the British leader out of the top two, or finish second with Hamilton failing to score. If Hamilton finishes ahead he will claim his second world drivers' title.
The two Mercedes men were a second clear of the field as they pursued their private duel for the drivers' crown.
Brazilian Felipe Massa was third fastest for Williams ahead of Ferrari's two-time champion Fernando Alonso of Spain in his final drive for the Italian team.
Alonso had been left without any running due an electrical problem in Friday's second practice session and took part in only half of Saturday's hour before withdrawing to preserve his engine.
His successor at Ferrari, four-time champion Sebastian Vettel was fifth quickest in his Red Bull ahead of Briton Jenson Button for McLaren.