Max Verstappen led the way in opening practice for the Mexican Grand Prix as Red Bull set the early pace.
Verstappen said on Thursday that he was out to stop Lewis Hamilton from winning his fifth world championship in style, and the Dutchman ended the opening running at the Autodromo Hermanos Rodriguez half-a-second clear of anybody else.
Daniel Ricciardo finished second with Hamilton only fifth, and Sebastian Vettel – who must win on Sunday to stand any chance of stopping his rival from taking the title – a distant seventh.
The Mexico City circuit sits 2,200 metres above sea level and acts as an equaliser in engine performance.
Therefore, the Renault in the back of Verstappen’s Red Bull, usually inferior to the might of Mercedes and Ferrari, was expected to be closer this weekend.
And the early signs were indeed promising for Verstappen, and his Red Bull team, with the 21-year-old 1.2 seconds faster than Carlos Sainz, a surprising third for Renault.
His team-mate Nico Hulkenberg finished fourth.
Hamilton needs to finish only seventh on Sunday to be sure of the championship, but the Briton will want to seal the title by winning the race here.
Yet, on the evidence of first practice, there is plenty of work for Hamilton and his Mercedes team to do.
The Englishman, who twice reported a drop on power with his Mercedes engine, finished 1.4 seconds behind Verstappen, while Valtteri Bottas, in the sister Silver Arrow, was two tenths back in sixth.
Vettel, 70 points behind Hamilton with only 75 remaining, finished the session in seventh, a full two seconds adrift of Verstappen’s time.
Kimi Raikkonen, who won in America last weekend, spun at Turn 6 before he finished eighth.
British teenager Lando Norris, running in place of Fernando Alonso for first practice, finished 15th, one place ahead of Stoffel Vandoorne in the other McLaren.