Lewis Hamilton started his quest for success at the United States Grand Prix with the fastest time in first practice.
The Mercedes driver, who will wrap up his fifth championship on Sunday if he outscores Ferrari’s Sebastian Vettel by eight points, finished ahead of team-mate Valtteri Bottas in the wet running.
Hamilton clocked a best lap of one minute and 47.502 seconds at the Circuit of the Americas, to end the session more than a second quicker than any other driver.
Hamilton, who has been in electrifying form to establish an almost-unassailable 67-point lead over Vettel with 100 remaining, completed just six laps in the damp conditions.
But he will no doubt be pleased with his speed in the wet, to lap 1.3 sec faster than Bottas, with persistent rain forecast for the remainder of practice and Saturday’s qualifying session, too.
Vettel finished fifth, two seconds down on Hamilton, and completed 18 laps.
The Red Bull pair of Max Verstappen and Daniel Ricciardo were the closest challengers to the Mercedes cars in third and fourth.
Hamilton will seal the championship on Sunday with three rounds remaining if he claims his fifth consecutive win in Austin, Texas, and Vettel fails to finish second.
Sauber driver Charles Leclerc was the biggest victim to fall foul of the tricky conditions after he spun into the gravel at the exit of the esses.
Leclerc returned to the track, but in doing so, dragged a large amount of sand back onto the tarmac and the session was temporarily suspended to deal with the mess.
There was also a hairy moment for the Force India mechanics when Esteban Ocon ran over his marks as he entered the pits and his quick-thinking crew had to jump out of the way.
Kimi Raikkonen was sixth for Ferrari ahead of the Renault of Carlos Sainz and Haas driver Romain Grosjean.
McLaren’s British teenager Lando Norris finished 12th as he continues to clock up the practice miles ahead of his rookie season next year.