Seven-times Formula One champion Lewis Hamilton set the pace in Friday's opening practice for the Bahrain Grand Prix ahead of team mate Valtteri Bottas who completed a one-two for Mercedes.
The Briton, who equalled Michael Schumacher's record haul of seven titles at the last race in Turkey, lapped the 5.4km Sakhir desert track in one minute, 29.033 seconds, 0.449 seconds clear of Bottas.
Sergio Perez in the Racing Point was third, 0.967 seconds off the pace.
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Carlos Sainz was fourth for McLaren, ahead of AlphaTauri's Pierre Gasly, with the Red Bull pair of Max Verstappen and Alexander Albon sixth and seventh respectively followed by Renault's Esteban Ocon.
Lance Stroll was ninth in the other Racing Point and Daniel Ricciardo rounded out the top 10 for Renault.
Charles Leclerc, who was on course for a pole-to-flag win in Bahrain last year, was 11th in his Ferrari. His team mate Vettel, the most successful driver in Bahrain with four wins, was 12th.
The session, which took place under overcast skies, was largely uneventful apart from occasional spins and lock-ups as drivers got to grips with the track.
Alfa Romeo reserve driver Robert Kubica made his fourth practice appearance of the season, taking over Kimi Raikkonen's car for the session.
At Williams, development driver Roy Nissany got some track time in Briton George Russell's car.
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