Ferrari driver Charles Leclerc led the way from Mercedes' George Russell as the inaugural Miami Grand Prix weekend got underway on Friday afternoon.
After an action-packed week of media activities, with Formula 1 rapidly increasing its presence in the United States, hot conditions greeted the drivers for their eagerly-anticipated first laps of the new Miami International Autodrome.
Unsurprisingly, all teams were keen to get out on track and gather data around the 5.412-kilometre track, which comprises 19 corners and three lengthy DRS zones.
Ferrari were the early FP1 pace-setters on the Medium compound tyre, as Leclerc led the way from teammate Carlos Sainz in the opening minutes, with Red Bull's Max Verstappen watching on.
Leclerc and Verstappen, separated by 27 points in the standings, both had close calls as they got up to speed, with the Monegasque escaping from a spin, and the Dutchman brushing against a wall.
Verstappen subsequently spent a chunk of the session stuck in the garage, as mechanics checked out an apparent issue on the rear of his RB18.
Result Free practice 1 - Miami
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Drivers start to explore the limits on Soft tyres
As the session wore on, and the track rubbered in, Leclerc worked his way down to a time of 1:31.098 on the Soft rubber.
Leclerc's benchmark put him just under a tenth clear of Russell, with Mercedes trialling a raft of new updates for the W13, having also promised to "experiment" throughout the weekend.
Verstappen made his way back out to post the third-fastest time, closely followed by teammate Sergio Perez, with AlphaTauri's Pierre Gasly completing the top five.
Sainz was sixth in the other Ferrari, setting his best effort on the Medium tyre after spinning and picking up a puncture at the start of his Soft-shod run.
Alex Albon and Williams were a surprise seventh, with Lewis Hamilton having to settle for eighth in his Mercedes after a compromised run on Softs.
The top 10 positions were rounded out by Haas' Kevin Magnussen and McLaren's Daniel Ricciardo.
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Bottas crashes out, pre-session drama involving Hamilton
The session was brought to a halt just after the halfway mark when Valtteri Bottas lost control of his Alfa Romeo and slid into the barriers at Turn 7.
With his car going in rearwards and sustaining plenty of damage, the yellow flags were initially waved, before the decision was taken to red flag proceedings, cutting around 10 minutes from the planned one hour of running.
Elsewhere, Alpine's Esteban Ocon has been called up to the stewards after a near-miss with Russell in the pit lane.
Ricciardo has also been summoned after his slow-moving car was narrowly avoided by Haas driver Mick Schumacher on the long straight between Turns 16 and 17.
Before the session got underway, there was plenty of drama in the form of a stand-off between Hamilton and the FIA, relating to the wearing of jewellery on track.
After Hamilton's press conference statements, and some initial confusion, it emerged that F1's governing body have given the seven-time World Champion an exemption for his "welded in" items.
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