AUSTIN (AFP) - Championship leader Lewis Hamilton completed a comfortable "double top" for Mercedes in Friday's (Oct 20) practice for this weekend's United States Grand Prix, the Briton topping both sessions as his title rival Sebastian Vettel struggled to keep pace for Ferrari.
The 32-year-old Briton, who can clinch his fourth world championship in Sunday's race if he wins and Vettel is outside the top five, dominated the day, winding up nearly four-tenths quicker than Dutchman Max Verstappen of Red Bull in the second session.
Vettel spun off into the gravel in his Ferrari early in the afternoon session, but managed to keep his engine running and drive back to the pits before winding up third.
Hamilton clocked a best time of one minute and 34.668 seconds in the second session, outpacing Verstappen, who had earlier confirmed he was extending his Red Bull contract to 2020, by 0.391 seconds and Vettel by 0.524 seconds.
Hamilton's Mercedes team-mate Valtteri Bottas was fourth ahead of Australian Daniel Ricciardo in the second Red Bull and 2007 champion Kimi Raikkonen in the second Ferrari.
Two-time champion Fernando Alonso was seventh fastest ahead of Felipe Massa of Williams and the two Force India cars of Sergio Perez and Esteban Ocon.
Debutant Brendon Hartley, the first New Zealander to race in Formula One for 33 years, was 17th on his first run with Toro Rosso.