Max Verstappen lost no time getting down to business in Abu Dhabi, the Red Bull driver leading the opening practice session at Yas Marina from Mercedes' Valtteri Bottas.
The Dutchman concluded FP1 just 0.196s ahead of the Finn while Lewis Hamilton was third, 0.346s behind his title rival.
Behind the leading trio, Sergio Perez and AlphaTauri's Yuki Tsunoda rounded off the top five.
Since Formula 1's last visit to Abu Dhabi, the Yas Marina circuit has been slightly revised, with the most significant changes taking place at the Turn 7 hairpin, which has been widened to offer better overtaking opportunities, at Turn 9 which is now slightly banked and around the hotel complex.
Overall, the teams' simulations are predicting a 10-second reduction in lap times.
In addition to the gripping title fight between Max Verstappen and Lewis Hamilton, this weekend's curtain-closer will also be the last races in F1 for Alfa chargers Antonio Giovinazzi and Kimi Raikkonen.
And as a reminder, the Iceman, who will head into a plush and well-deserved retirement on Sunday evening, is set to start his 350th Grand Prix.
Also, Williams junior Jack Aitken was back in the driver's seat for FP1, while George Russell will take his usual seat in the FW43B later this afternoon.
Track temps sat at 39.4° while air temp was a warm 27° when the final FP1 session of 2021 kicked off.
Verstappen was on the radio at the outset to complain about a slightly offset steering wheel, while Hamilton, his nemesis, set the first benchmark at 1m27.148s.
The two title protagonists, both shod with the soft tyre, traded places at the top of the timesheet in the opening part of the session, pushing times into the 1m25s bracket, with Verstappen slightly ahead.
Behind the leading duo, their respective wingmen were lined up just behind, with Perez ahead of Bottas, while AlphaTauri's Pierre Gasly sat in P5 just ahead of Norris.
As the session entered its second half, Verstappen upped the pace, lowering his best time to 1m25.009s. Bottas followed suit and slotted into P2, 0.196s adrift from the Red Bull driver.
Lap time deletions at Yas Marina's Turn 16 were a common theme during the opening session, including for Hamilton who had his personal best canceled for running beyond the white line at the corner.
However, the first work session of the day concluded in an orderly fashion, with Verstappen and Red Bull drawing first blood, the Dutchman heading Bottas, Hamilton, Perez and the impressive Yuki Tsunoda.
Behind the top five, Fernando Alonso headed Gasly, Ferrari's Charles Leclerc and Carlos Sainz and Aston Martin's Sebastian Vettel.
Both McLaren drivers, Lando Norris and Daniel Ricciardo, enjoyed a leisurely start to their race weekend, but among the lower tier runners, Aitken enjoyed a solid session, the Williams junior outpacing teammate Nicholas Latifi.
As predicted, lap times tumbled on Yas Marina's revised layout, with Verstappen's best lap quicker by almost ten second to his pole position time form 2020.
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