Full FP1 session times HERE
Lewis Hamilton set the fastest time of FP1 for the United States Grand Prix as McLaren showed impressive pace.
Jenson Button was lapping on his own early in the session but was quick throughout and ended up third fastest, just 0.378s off Hamilton's pace-setting time of 1:39.941. Nico Rosberg – 17 points adrift of his team-mate in the drivers' championship with three races remaining – was second quickest in the other Mercedes, albeit less than 0.1s ahead of Button.
Daniil Kvyat was fourth fastest for Toro Rosso – 0.946s slower than Hamilton – ahead of Button's McLaren team-mate Kevin Magnussen who was over a second off the pace. Fernando Alonso was sixth ahead of Sebastian Vettel, while Felipe Nasr had an encouraging run for Williams with the eighth quickest time.
Nico Hulkenberg and future Toro Rosso race driver Max Verstappen completed the top ten, with just 18 cars taking part due to the absence of Caterham and Marussia.
First practice was a difficult session for Daniel Ricciardo as he completed just five laps before being forced to pit with an ERS issue which confined him to the garage for the rest of the morning. He ended up 17th quickest with only Romain Grosjean behind him. Grosjean was running a 2015 test nose for Lotus in the early part of the session – with the design similar to the one on this year's Ferrari – before reverting to the twin tusk nose late on.
There were few incidents during the session, with Adrian Sutil having a spin in his Sauber at Turn 19, while Pastor Maldonado escaped without damage when he also spun at high speed exiting Turn 6.
Following the chequered flag there was a strange situation when Kimi Raikkonen followed a Lotus in to the pit lane and took to the inside lane in an apparent attempt to overtake, but appeared to be so preoccupied with watching the car alongside him that he completely missed the Ferrari garage. As a result, Raikkonen had to stop further down the pit lane and wait for his Ferrari mechanics to wheel him back.