Sebastian Vettel will line up for his 100th Formula One race in pole position on Sunday after dominating Saturday's United States Grand Prix qualifying session with a dazzling display of pace in his Red Bull car.

The 25-year-old German, who needs to out-score nearest rival Fernando Alonso of Ferrari by 15 points to become the youngest triple champion in F1 history, was fastest throughout the session after topping the times in all three practice sessions.

He clocked a final best lap time of one minute and 35.657 seconds in the final seconds of a closely-fought hour of speed to leave nearest rival Lewis Hamilton adrift by a tenth of a second in his McLaren.

Vettel's Red Bull team-mate Mark Webber was third fastest ahead of Romain Grosjean of Lotus, but the latter will have to drop five places because his team fitted a new gearbox to his car before the session.

That meant that Alonso, who qualified ninth, will move forward one place to eighth on the grid for the penultimate race of the season at the new Circuit of the Americas, 25 kilometres out of downtown Austin.

It was Vettel's sixth pole this season and the 36th of his remarkable career, and to mark the occasion, he added a Texan lone star to his helmet design.

"We're very pleased," said Vettel.

"We started on the right foot in first practice. It was extremely slippery to start with. The circuit is brand new and it takes a while to come in, but it was quite a lot of fun to slide a couple of corners.

"In the final section, I would have loved to have gone a bit quicker. It was a bit closer than I wanted, but it is fantastic for me to start on the front and on the clean side."

Hamilton said: "I'm not really concerned about the first corner, I'm more concerned about being on the dirty side of the grid.

"I did a launch there earlier and it was quite slippery. My aim is to get a good getaway. I don't want to get in the way of Sebastian's race, but I do want to win. I will try my best to get through the first turn cleanly."

Webber, who starts third and may play an important role in defending Vettel's position, said: "I'm happy with qualifying. I was pretty happy with the last part of Q3.

"I had to manage a little problem with the car, but the two guys ahead of me were pretty quick and did very strong lap times.

"Overall, I'm happy to be third on the grid. We can have a strong grand prix from there. It's a great job by the team. We've got our eye on the constructors' championship and trying to put that to bed."

Despite his low grid position Alonso remained optimistic.

"I'll try to move up the grid on Sunday and I still believe I can score more points than Sebastian, I need to keep my confidence."

Kimi Raikkonen, who won the Abu Dhabi Grand Prix two weeks ago, was fifth for Lotus ahead of retirement-bound seven-time champion Michael Schumacher in his Mercedes.

Alonso's Ferrari team-mate Felipe Massa qualified seventh ahead of ever-improving Nico Hulkenberg of Force India, with Alonso ninth and Pastor Maldonado 10th for Williams.

Briton Jenson Button, in the second McLaren, failed to make the cut to the top-ten shootout after losing power due to a throttle pedal problem in Q2 on a day of clear skies and rising temperatures following a cold morning.