Lando Norris set a commanding pace in practice for the United States Grand Prix to throw down the gauntlet to title rival Oscar Piastri.
Norris has arrived in Austin 22 points adrift of his McLaren teammate in the standings.
The British driver is facing unspecified "repercussions" from his own team after McLaren decided he was responsible for banging wheels with teammate Piastri on the first lap in Singapore a fortnight ago.
It is understood those consequences will be sporting ones and Norris suggested it could even be something that counts against him for the rest of the season.
McLaren CEO Zak Brown said they viewed Norris' indiscretion as "minor" and the consequences would be proportionate, adding that their only rule is not to touch each other.
His quest to overhaul Piastri and clinch the drivers' championship, having finished ahead of his teammate at each of the last three races, began in thumping fashion in the only practice session of the weekend.
He ended the session 0.279 seconds clear of third-placed Piastri, with Sauber's Nico Hülkenberg claiming an impressive second ahead of Fernando Alonso in fourth.
Max Verstappen, who has tentatively emerged as a title hopeful as he chases a fifth successive crown, is 63 points behind Piastri heading into the weekend. He was fifth fastest, over three tenths adrift.
There are 33 points up for grabs across the weekend in Austin, with Saturday's sprint followed by Sunday's main race.
Lewis Hamilton, a five-time winner at the Circuit of the Americas, enjoyed a strong opening session and was over half-a-second clear of the field on the initial hard-tyre runs.
Once the soft tyres went on, he slipped down the order in his Ferrari, finishing the session down in eighth.
Qualifying for the sprint gets under way at 16:30 local time (22:30 BST).