Sergio Perez underlined Red Bull's pace by finishing fastest in first practice for the Bahrain Grand Prix.
The Mexican set a lap time of one minute, 32.758secs to finish 0.438s faster than Aston Martin's Fernando Alonso.
The Spaniard, making his debut for the Silverstone-based outfit, backed up the team's pre-season pace to split Perez from double world champion team-mate Max Verstappen.
Ferrari, meanwhile, endured a difficult session with rear wing issues and a spin for Carlos Sainz setting back its run plans.
Perez enters the new season knowing he must close the gap to Verstappen and a strong opening hour to the year will fill the Mexican with confidence.
Lando Norris put McLaren's pre-season struggles behind him to finish fourth fastest, although the usual caveats of fuel loads, engine modes and run plans must be taken into account.
Next came Charles Leclerc, one and a half seconds down on Perez with Ferrari having to revert from a single-pillar rear wing design due to excessive horizontal travel. The Monégasque's lap time was set on the mediums, however.
Team-mate Carlos Sainz lost a set of mediums when wildly spinning at turn nine, his SF-23 unsettled when hitting an aggressive bump at the turn-in point.
Lance Stroll returned to action following his pre-season cycling accident to jump to sixth in the second Aston Martin, despite losing vital time owing to an ignition problem.
Haas driver Kevin Magnussen finished seventh ahead of Alfa Romeo duo Zhou Guanyu and Valtteri Bottas, with the Hinwil-based team performing solidly.
Lewis Hamilton was involved in drama before track action for the season had even started with a summons to the FIA race stewards over a potential breach of the jewellery ban.
The seven-time champion was handed an exemption over fears of disfigurement and when Hamilton did take to the wheel of the W14, he enjoyed a much less dramatic hour of running, completing 13 laps.
Mercedes team-mate George Russell followed in 11th, with rookie Oscar Piastri behind. The McLaren driver almost rotated the MCL60 at high speed through turn seven but shrewdly caught the slide to continue.
Yuki Tsunoda finished 13th fastest in the lead AlphaTauri, four tenths faster than team-mate Nyck de Vries with Haas' Nico Hulkenberg and Alpine's Esteban Ocon separating the duo.
Pierre Gasly was down in 17th ahead of only the two Williams drivers and Sainz. Rookie Logan Sargeant completed 24 laps ahead of his first weekend.
Bahrain Grand Prix first practice results
1. Sergio Perez [Red Bull] - 1:32.758
2. Fernando Alonso [Aston Martin] - +0.438secs
3. Max Verstappen [Red Bull] - +0.617s
4. Lando Norris [McLaren] - +1.407s
5. Charles Leclerc [Ferrari] - +1.499s
6. Lance Stroll [Aston Martin] - +1.540s
7. Kevin Magnussen [Haas] - +1,644s
8. Zhou Guanyu [Alfa Romeo] - +1.817s
9. Valtteri Bottas [Alfa Romeo] - +1.931s
10. Lewis Hamilton [Mercedes] - +2.159s
11. George Russell [Mercedes] - +2.208s
12. Oscar Piastri [McLaren] - +2.239s
13. Yuki Tsunoda [AlphaTauri] - +2.257s
14. Nico Hulkenberg [Haas] - +2.285s
15. Esteban Ocon [Alpine] - +2.347s
16. Nyck de Vries [AlphaTauri] - +2.644s
17. Pierre Gasly [Alpine] - +2.697s
18. Logan Sargeant [Williams] - +2.991s
19. Alex Albon [Williams] - +3.260s
20. Carlos Sainz [Ferrari] - +3.314s
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