Championship leader Max Verstappen struggled on the first day of practice at the Las Vegas Grand Prix, ending it down in 17th place in his Red Bull.
McLaren’s Lando Norris, who has a slim chance of the championship, fared better, ending up second fastest behind Mercedes driver Lewis Hamilton.
Hamilton topped both sessions, first from team-mate George Russell and then Norris.
Verstappen, who can clinch his fourth drivers’ title this weekend, ended up two seconds off the pace after a difficult day.
The Dutchman will win the title as long as he does not lose more than two points to Norris in the race on Saturday (06:00 GMT Sunday).
Verstappen did not complete a lap on the fastest soft tyres, but nevertheless acknowledged that Red Bull had not had a successful day.
“We struggled a lot with making the tyres work, over one lap especially,” he said.
“Long runs started off a bit more competitive but even there we need to fine-tune a few things.
“The one-lap pace is quite far off. Of course it is quite unique conditions and very cold and we need to understand what we are doing wrong at the moment.
“It feels massively tyre-related, the balance is not that wrong, but we have no grip. It is like driving on ice at the moment.”
Hamilton was 0.011 seconds quicker than Norris in the second session, and 0.396secs clear of Russell in the first.
