Valtteri Bottas led the field in Friday's opening practice session at the Circuit of the Americas, the Finn edging teammate Lewis Hamilton by 0.045s.
But the Mercedes pair's margin over third-place man and arch-rival Max Verstappen was almost a full second, an advantage that confirmed the Brackley squad's apparent superiority over Red Bull.
Behind the trio, Ferrari's Charles Leclerc and Carlos Sainz led the midfield.
After two years away, Formula 1 has set up shop once again back west, in the great Lone Star State of Texas, the perfect venue for another shootout between the sport's top protagonists.
F1's absence from Austin logically elevates the importance of Friday's practice session, especially as a new tarmac equates to a learning process regarding tyres for teams and drivers, and Pirelli.
Cars took to the track under sunny skies and a warm 27°C. Unfortunately, it was a troubled start for Alpine's Fernando Alonso who ground to a halt just three minutes into the session, the victim of an apparent mechanical issue.
The session resumed after a short red flag interruption. Lap time deletions ensued as drivers got re-acquainted with the track and their car's limits, while Charles Leclerc headed back to the pits for his team to carry out a clean-up after a visit to the gravel trap at Turn 6 for the Ferrari driver.
At the top of the timing screens, a soft-shod Hamilton led the field with a 1m36.812, edging McLaren's Lando Norris by just 0.043s.
But the two Brits were overhauled in short order by Perez, the Mexican opting for the hard tyre at that point of the session.
However, Hamilton, despite complaining about overheating his rear tyres, responded to take back the top spot from Perez, Norris, Bottas and Verstappen.
Sebastian Vettel briefly went fastest; but the Aston charger's time was justifiably deleted for running wide at Turn 9. But a good effort by Leclerc moved the Monegasque up to P2, 0.220s behind Hamilton.
But with 20 minutes left on the clock, Verstappen, running on the softs, put in a 1m36.049 flyer that beat Hamilton's best by 0.332s. However, once again, the Mercedes driver would have none of it, and he duly lowered the benchmark by almost a second to 1m35.096s.
To further prove Mercedes' point, or pace, Bottas went 0.222s faster than his teammate to lead a rock-solid Merc 1-2, which is how the first practice session of the day concluded.
The standard disclaimers applied regarding fuel loads and engine modes, but Mercedes' speed implied that Red Bull may have some catching up to do.
Behind the Bottas-Hamilton-trio, Ferrari's duo of leclzerc and Sainz lined up P4 and P5, with AlphaTauri's Pierre Gasly heading Perez, Norris and the Alfa's of Antonio Giovinazzi and Kimi Raikkonen.
Russell led the second half of the field which included both Aston Martin and Alpine drivers and a low-key Daniel Ricciardo. At the tail end of standings, Haas' Mick Schumacher and Nikita mazepin predictably bookended the order.
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