US Grand Prix – Lewis Hamilton topped second practice for Mercedes ahead of Max Verstappen and title rival Sebastian Vettel.
The championship leader set a new ultimate lap record of 1:34.668 on the ultrasoft tyres, four tenths ahead of Verstappen.
The Dutchman is due to take a 15-place grid penalty after taking on a new internal combustion engine from Renault, which is set to be put in overnight.
Renault have brought one for each team it supplies of the new engine, the design of which is a step closer to what the French manufacturer is aiming to bring to the start of the 2018 season.
Nico Hulkenberg, who will take a total of 20-places in grid penalties for power unit element changes, will be running the new engine on the Renault works team, as will Formula 1 debutant Brandan Hartley for Toro Rosso, who takes a 25-place penalty.
Vettel spun on the way into the penultimate corner early in the session, ditching his Ferrari in the gravel and flat-spotting his soft tyres through to the canvas.
The German was unable to put in a proper race simulation and later complained of an issue with the front axle, saying it “feels like jelly” on the team radio. He ended FP2 half a second away from pacesetter Hamilton.
Valtteri Bottas was fourth fastest, six tenths off his team mate, ahead of Daniel Ricciardo and Kimi Raikkonen.
Fernando Alonso was seventh for McLaren, 1.6s off the pace, ahead of Felipe Massa and the two Force Indias of Sergio Perez and Esteban Ocon.
Haas had an eventful start to the session as both drivers spun early in their initial runs, with Romain Grosjean losing the rear of his car at the Turn 11 hairpin and Kevin Magnussen spinning off at the penultimate corner.
The pair then tripped over each other in the stadium section at Turn 16 when Magnussen complained that his team mate was blocking him.
Lance Stroll suffered from a loose headrest during his race simulation and was further confined to the garage with an exhaust issue.
