Lewis Hamilton completed a hat-trick of first place finishes during practice at the Circuit of the Americas. The championship chasing Brit clocked in a 1:34.478 in the final session, which was the quickest time set all weekend.
Hamilton's title rival Sebastian Vettel followed but was only less than a tenth of a second down. Third and fourth place was also occupied by a Mercedes and Ferrari, with Valtteri Bottas leading his Finnish compatriot Kimi Raikkonen.
Max Verstappen was fifth, but his session was overshadowed by the confirmation that he will take a grid penalty for Sunday's race. The Dutchman will be penalised 15 grid places due to his use of a sixth engine and sixth MGU-H.
Felipe Massa once again demonstrated the pace of the FW40 in Austin, ending the sixty minutes of running in sixth place. He was ahead of the two Renault's of Nico Hulkenberg and Carlos Sainz, who were separated by just five-hundredths of a second.
Daniel Ricciardo failed to impress heading into qualifying, as his best lap only put him in ninth place. The Australian led both Force India's, with Sergio Perez rounding out the top ten and Esteban Ocon concluding practice in eleventh position.
Lance Stroll was twelfth but will be hoping to close the margin to his teammate Massa in qualifying. Behind Stroll was the McLaren pair, with Fernando Alonso's time pipping Stoffel Vandoorne's by just over three and a half tenths.
Brendon Hartley was fifteenth, while Kevin Magnussen was sixteenth. Magnussen's teammate Romain Grosjean had his day ended prematurely after his spun his car at Turn 7 and found it beached in the gravel traps.
Grosjean ended the session in nineteenth, as the Sauber's of Marcus Ericsson and Pascal Wehrlein sandwiched themselves in between the two Haas'. Daniil Kvyat, who incurred a problem early on, rounded out the timesheets.
15:10 - 17:10