Mercedes drivers and championship rivals Lewis Hamilton and Nico Rosberg posted the fastest times in Saturday's final practice before qualifying for the U.S. Grand Prix.
Hamilton's best lap on a chilly morning at the Circuit of the Americas was 1 minute, 37.107 seconds, .883 seconds quicker than Rosberg. Hamilton had to recover from a late spin and trip to the garage in the session before posting his fastest time.
Hamilton leads Rosberg by 17 points in the driver's championship with three races left.
Sunday's race will be run against the backdrop of tensions between Formula One's wealthiest teams and those struggling to survive. Two teams, Marussia and Caterham, won't race Sunday because of financial problems, dropping the grid to 18 cars, the smallest in nine years.