World champion Lewis Hamilton was fourth fastest in second practice for the Abu Dhabi Grand Prix.
With his fifth title already safely secured, Hamilton, 33, is hoping to sign off with his 11th victory of a remarkable year.
But the Mercedes star finished 0.207 seconds slower than team-mate Valtteri Bottas in the final running of the day at the Yas Marina circuit.
Hamilton, sporting a gold crash helmet and number one on his car this weekend to celebrate his latest championship success, faced a summons to the stewards after crossing the white line as he entered the pits.
The British driver is likely to be handed only a reprimand.
Bottas is searching for his first victory of an inauspicious campaign. The Finn finished four hundredths ahead of Max Verstappen in the early-evening dark.
Daniel Ricciardo, taking part in his 100th and final race for Red Bull before he moves to Renault next season, finished third.
Ferrari, looking to banish memories of their late-season collapse which allowed Hamilton to sew up the title more easily than he might have expected, occupied fifth and sixth places on the time sheets.
Kimi Raikkonen, whose long association with the Italian team will end with Sunday's race, held a slim advantage over Sebastian Vettel.
Fernando Alonso will bring down the curtain on the second longest career in Formula One under no illusions that he can add to his 32 victories.
It is more likely that the two-time world champion will be squabbling for the minor points come Sunday, his 312th and final start.
Here, he finished 13th for McLaren, 1.5 sec off the pace.
In first practice earlier in the day, Verstappen set the pace as Red Bull continue to end the season with a surge of form.
Verstappen, who was unlucky not to win when taken out while leading the Brazilian Grand Prix a fortnight ago, led Ricciardo in a Red Bull one-two.