Sebastian Vettel maintained his total domination of practice at the United States Grand Prix on Saturday morning when he topped the times for Red Bull for a third successive session ahead of Sunday's showdown, his 100th race in Formula One.
The 25-year-old German, who needs to outscore nearest rival Fernando Alonso of Ferrari by 15 points to become the youngest triple champion in F1 history, clocked a fastest lap in one minute and 36.490 seconds to emerge fastest.
That was enough to leave him nearly three-tenths of a second clear of nearest challenger Lewis Hamilton who, in his penultimate race weekend with McLaren before joining Mercedes next year, recorded a best time of 1:36.748.
Both men clocked their times in a busy final flurry of activity in the final minutes of the hour-long session run in cold conditions, but in front of a big crowd dressed in winter jackets, at the new Circuit of the Americas 25 kilometres out of downtown Austin. Venezuelan Pastor Maldonado was third fastest for Williams.