Vettel fastest in first US GP practice session
Sebastian Vettel issued an early warning to Fernando Alonso that he is not prepared for their title fight to go down to the wire.
In the opening practice session at the $400m (€313.6m) Circuit of The Americas that plays host to the first United States Grand Prix for five years, Vettel left his rivals in the shade come the end.
It is, of course, still early days on a track still very green and needing to be rubbered in, but as a potential marker, it will have had an effect.
Vettel needs to finish 15 points clear of Alonso on Sunday to become only the third driver in Formula One history - Juan Manuel Fangio and Michael Schumacher the others - to claim three titles in a row.
Organisers predicted a lap time of one minute 37 seconds for the 5.516km track that has 'borrowed' a number of features from other circuits.
Vettel, however, finished the initial 90 minutes with a time of one minute 38.125secs, and that on the hard, slower tyre compared to the option of the faster medium this weekend that was never used by any driver during FP1.
The opening laps were naturally cautious, with the track noticeably slippy, and with the first timed lap set by Sauber's Kamui Kobayashi of one minute 55 seconds.
Eventually McLaren's Lewis Hamilton took over proceedings and led the way for a lengthy period until the final 10 minutes when Vettel broke the back of the track.
The 25-year-old Red Bull star, who is currently 10 points clear of Alonso, finished 1.418secs clear of Hamilton, the biggest margin at the end of any practice session this season.
Naturally, it is not known what fuel level Vettel was running, but even so it was still an impressive margin, with Alonso third on the timesheet, 2.212secs adrift in his Ferrari.
The top three teams occupied the top six places, with Jenson Button in his McLaren, Red Bull's Mark Webber and Ferrari's Felipe Massa fourth, fifth and sixth respectively, all around 2.5secs down.
Force India's Nico Hulkenberg was the best of the rest ahead of Kobayashi and team-mate Sergio Perez in eighth and 10th, with Nico Rosberg in his Mercedes splitting the Sauber duo.
Paul di Resta, apparently struggling badly with the balance of his Force India car, was 11th quickest, 3.658secs behind Vettel, and 0.8secs down on team-mate Hulkenberg.
The Lotus duo of Kimi Raikkonen, who gave the team their first win this season last time out in Abu Dhabi, and Romain Grosjean were a lowly 14th and 15th but with the prospect of more to come.
At the bottom, and clearly out of his depth on this occasion, was HRT reserve Ma Qing Hua, the Chinese finishing 10.434secs off the pace, and 1.7secs behind team-mate Pedro de la Rosa.