Valtteri Bottas led a Mercedes 1-2 during the opening practice session for the Mexican Grand Prix in sunny conditions at the Autódromo Hermanos Rodríguez.
Bottas clocked a time of 1:17.824 on Ultrasoft tyres as several drivers struggled with the dusty, low-grip conditions at the venue.
Lewis Hamilton, who can clinch his fourth world title on Sunday, finished 0.466s behind his team-mate, also on the purple-banded compound, having recovered from a grassy excursion at Turn 2.
Max Verstappen placed third for Red Bull, in front of team-mate Daniel Ricciardo, and Ferrari pair Sebastian Vettel and Kimi Räikkönen, as the quartet ran Supersoft tyres.
Both Ferrari drivers had moments; Vettel ran wide at both Turn 1 and Turn 8, while Räikkönen spun through Turn 6.
Sergio Pérez led an evenly-spread midfield group in seventh position, in front of Fernando Alonso, Felipe Massa, Nico Hülkenberg, Carlos Sainz Jr. and Lance Stroll.
A gap of over a second followed back to Kevin Magnussen, with Sauber’s Pascal Wehrlein 14th.
Ferrari-backed Antonio Giovinazzi and Charles Leclerc received further Formula 1 experience with Haas and Sauber respectively, as they continued their push for a 2018 seat, placing 15th and 16th.
Sean Gelael had another outing with Toro Rosso, spinning through Turn 6, while Brendon Hartley suffered an engine issue in the sister STR12, briefly causing the Virtual Safety Car to be implemented.
Force India’s Alfonso Celis Jr. was afforded a run on home soil but caused a red flag when he spun into the barriers at Turn 16, sustaining rear-end damage to the VJM10.
Stoffel Vandoorne made only a brief appearance, running three installation laps, before Honda detected an issue with his Spec 3.8 power unit, newly installed prior to the opening practice session.
Vandoorne thus took no further part in the session, and will take on a spare Spec 3.7 power unit, meaning no additional penalties are to follow at this stage.
Vandoorne is already set to receive a 35-place grid drop due to taking on the now-replaced new power unit.
