Mercedes' contenders enjoyed a promising start to their Miami GP weekend, with George Russell and Lewis Hamilton taking full advantage of the track's evolution, the pair topping the timesheet in the final seconds of the session.
Both drivers set their quickest lap on the soft tyre, as did third-placed man Charles Leclerc who completed the top three for Ferrari while Max Verstappen and Carlos Sainz closed out the top five.
Red Bull's Sergio Perez was unusually absent from the front of field, while Haas' Nico Hulkenberg – an early frontrunner – brough out the red flag after crashing heavily at Turn 3.
Air temperatures at the Miami International Autodrome were sat at a summery 29° C while track temps were at 50°C when everyone lined up at the end of the pitlane at the start of FP1.
It was the start of a very special weekend for local fan favourite Logan Sargeant, the young American racing at home – literally just 15 minutes from his parents' house – for the first time since his karting days.
At the outset, Russell radioed in to complain of vibrations in his steering. The Mercedes driver urged his team to solve the issue "even if it takes 30 minutes". The Brackley squad duly undertook a steering rack change on the Briton's W14.
Meanwhile Hamilton went fastest, but the seven-time world champion was almost immediately demoted to second by Verstappen.
The two drivers traded fastest laps in the first fifteen minutes of the session, with Max eventually gaining the upper hand by over a full second.
Times continued to drop as the track evolved, with Leclerc and Alonso both leapfrogging Hamilton but remaining well behind Red Bull's Verstappen.
Flying his team's American flag, Nico Hulkenberg put in an extra effort to go fastest on the soft tyre as the session approached its halfway point, the German clearing Verstappen by 0.434s.
Adding to Haas' exposure, Kevin Magnussen slotted into third, but seconds later there was drama in US outfit's camp when the Hulk lost it when he ran slightly off-line through Turn 3 and veered into the wall.
As a reminder Miami was resurfaced since last year and the new track surface is offering a much higher level of grip.
The incident logically brought out the red flag as everyone returned to the pits and the marshals evacuated the badly bruised Haas.
The action resumed with 18 minutes left on the clock.
Shod with the soft tyre, Verstappen set a new benchmark time with a 1m30.549s that edged Leclerc by 0.523s, with Alonso positioned in third position.
But Sainz, relatively discrete up to then, powered up to second, but the Spaniard was quickly outdone by Leclerc, the Monegasque reducing his deficit to Verstappen to 0.253s.
With track evolution more than ever in play, both Mercedes drivers exploited the extra grip and powered to the top of the timesheets with just 60 seconds left on the clock, with Russell's 1m30.125s edging Hamilton by 0.212s.
Behind the leading Mercs, Leclerc sat ahaed of Verstappen, Sainz, Alpine's Pierre Gasly, Alonso, Stroll and Hulkenberg.
Esteban Ocon led the second half of the field from Perez who was conspicuously absent from the top-ten, while Oscar Piastri, Magnussen, Valtteri Bottas and Alex Albon rounding off the top 15.
Norris, Zhou Guanyu, Yuki Tsunoda, Sargeant and Nyck de Vries closed out the field.
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