Valtteri Bottas edged out Lewis Hamilton as Mercedes booked a 1-2 in first practice on Friday morning in Mexico City - although Red Bull and Ferrari shadowed the Silver Arrows despite using a harder tyre compound for their respective fastest runs.
That provided particularly good news for Red Bull - both Max Verstappen and Daniel Ricciardo finished within 0.6s of Bottas, which is less than the estimated delta between the ultrasofts used by Mercedes and the supersofts that both Red Bull and Ferrari elected to stay on.
Ferrari's Sebastian Vettel wound up fifth, a few tenths ahead of team mate Kimi Raikkonen. Both men had minor offs - as did Hamilton - while Verstappen experienced an early end to his session due to a fundamental set-up change.
There was worse fortune down at Force India: Mexican Alfonso Celis, standing in for Esteban Ocon, hit the wall exiting Turn 16, damaging the rear of his car and triggering a brief red flag period. He too was unable to rejoin, winding up 19th overall - just ahead of Stoffel Vandoorne, whose McLaren was struck by early engine gremlins that limited him to just three laps. Bottas in contrast was the morning's busiest runner with 41, with his benchmark time the fastest ever recorded on the current layout of the Mexico City circuit.
Home hero Sergio Perez upheld his countrymen’s hopes with seventh fastest time of 1m 19.240s for Force India, using the supersofts. He headed four ultrasoft runners: Fernando Alonso’s McLaren, Felipe Massa’s Williams, and the tightly matched Renaults of Nico Hulkenberg and Carlos Sainz, who were split by just 0.02s.
In what was a very exploratory session, Antonio Giovinazzi was the leading ‘substitute’ driver, taking Romain Grosjean’s Haas to the 15th fastest time, ahead of Charles Leclerc in Marcus Ericsson’s Sauber and Sean Gelael, who briefly spun Pierre Gasly’s Toro Rosso.
Toro Rosso’s other runner, Brendon Hartley, competing in his second ever event, met with troubles that momentarily stopped him at Turn 4 halfway through. He managed to get going again but spent the rest of the session in the garage.