Ahead of today's sole practice session, the air temperature is 29 degrees C, while the track temperature is 48 degrees. Though bright there is a 10% chance of rain.
In terms of upgrades, Red Bull has a new Floor Edge, Mercedes a new Floor Body, Cooling Louvres, Front Wing and Front Suspension, while McLaren has a new Front Wing, Front Suspension, Front Corner, Floor Body, Sidepod Inlet, Coke/Engine, Cooling Louvres, Rear Suspension, Rear Corner and Beam Wing.
Aston Martin has a new Front Wing, Coke/Engine, Rear Wing, Beam Wing and Chassis Scoop, while Williams has a new Front Wing, RB a new Floor Body and Diffuser, Stake a new Front Wing and Rear Wing and Haas a new Floor Body.
Ferrari and Alpine have not brought any updates, though the Maranello outfit has a spiffing, very blue, new livery, and the French outfit is understood to have met the weight limit for the first time this year... we know the problem.
As the lights go green Magnussen leads the way, followed by Ocon, Piastri, Norris and Gasly, the teams having only this next hour to try those updates... which means a lot of work, in particular, for the Woking pair.
As more drivers head out, most are on hards though a couple have opted for mediums.
"Something doesn't feel right," reports Norris, "it's much harder to turn right than it is to turn left." He subsequently pits.
The 19 corner track features 7 right-handers and 12 left-handers.
Ocon posts a benchmark 32.387 but this is soon beaten by Piastri (31.491) on hards.
Incidentally, Williams finally has a spare car available.
A 31.127 sees Hamilton go quickest on the medium.
Sargeant heads out leaving his teammate as the only no show.
Piastri reports that his steering is "quite heavy".
Out comes the double yellows as Leclerc spins at Turn 16. As the Monegasque unsuccessfully attempts to turn his car facing the correct way, it affords his rivals a good opportunity to check out the new livery.
Replay shows him losing the car as he ran over the inside kerb.
Unable to get the car going again, the session is red-flagged and Leclerc climbs from the Ferrari.
Shortly before the incident, Verstappen had gone quickest - quelle surprise - with a 31.071, ahead of Hamilton, Perez - all on mediums - Magnussen, Piastri and Sainz.
The session resumes with 44 minutes remaining, Sargeant leading the field back on to the track.
Norris is among those that heads out, however he reports that his steering "feels the same".
Sargeant goes twelfth with a 32.736 while teammate Albon posts a 31.937 to go seventh.
As Perez goes quickest (29.632) and Russell second (29.986), Aston Martin appear to be scrubbing their hard tyres.
"I'll just continue and see if it changes at all," says Norris as he insists the issue hasn't been resolved.
A 30.492 sees Tsunoda go fifth with Alonso going sixth with a 30.779, both on the white-banded rubber.
"It's surging in third gear," reports Albon, "very similar to China."
Verstappen lock-up at Turn 17 and heads down the escape road.
Sainz goes third on the hards, while Hamilton (medium) improves to second with a 29.759.
Zak Brown confirms that only Norris has the full package of upgrades, while Piastri only has "half".
Sainz goes quickest with a 29.346 as Zhou goes fifth, the Chinese driver, like Stake teammate Bottas, yet to secure his seat for next season.
Verstappen reports "front-locking too quickly at the peak", as the cameras pick up on him taking a pounding as his car bounces over the kerbs.
Norris improves to fifth ad Piastri sixth, both on the hards.
"Lando's issue is an asymmetric power steering assistance," says Zak Brown. "Not to do with upgrades. We have made some changes during the session to improve it and will fix it after the session."
Piastri improves to third with a 29.692.
Alonso is said to be unhappy with both the front and rear of his car... the middle bit, he likes.
Norris goes second with a 29.495, as Verstappen drops to 16th following his 17-lap run.
With 15 minutes remaining, Albon is the first to switch to the red-banded rubber. Zhou follows suit.
As more drivers switch to the softs, Zhou fails to improve and remains seventh, while Albon aborts. Zhou complains of a lack of grip.
Following a nasty moment in Turn 7, Albon asks: "What is going on... was that rear-locking or what?" "Rear-locking," he is told.
Meanwhile, Gasly goes quickest (29.175) on the softs, as Albon improves to fourth with a 29.540.
"That was a gust of wind, tail of wind," Verstappen is advised.
Russell goes quickest in S1, and again in S2, at the line he posts a 28.910 to go quickest, ahead of Sainz who had just posted a 28.979.
"I have no grip," complains Verstappen, "it's like driving on eggshells", as Hamilton goes third and Magnussen sixth.
Indeed, it appears the softs don't actually last a full lap.
Tsunoda goes fourth, ahead of Gasly, Magnussen, Hulkenberg and Ocon.
Quickest in S2, Perez crosses the line at 28.868, 0.042s up on Russell, despite a mistake in S1.
His teammate has dropped to 19th.
Alonso shuns the offer of softs and instead opts to continue on the hards.
Verstappen goes quickest in S2, and despite a mistake in Turn 17 goes quickest with a 28.959.
No sooner has Russell improves to 28.784, than Sainz and Piastri also improve, the Australian going second with a 28.700.
The session ends. Verstappen is quickest, ahead of Piastri, Sainz, Russell, Stroll, Perez, Hamilton, Tsunoda, Ocon and Gasly.
Ricciardo is eleventh, ahead of Magnussen, Hulkenberg, Albon, Zhou, Norris, Bottas, Sargeant, Alonso and Leclerc.
Check out our Friday gallery from Miami here.
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