Sebastian Vettel was the fastest man on track again in Free Practice 3, the final practice session ahed of qualifying for this weekend's United States GP.

Vettel's team mate Mark Webber confirmed the Red Bull's pace in Austin by locking up second place, leaving Lewis Hamilton as the best of the rest for Mercedes and Sauber's Nico Hulkenberg threatening to once again be a significant factor on qualifying and on the grid by taking up residence in fourth at the end of the hour.

Where there had been dense fog on Friday morning, there was only a light mist at the same time on Saturday as the cars exited pit lane at the start of the session. Despite the the track still being unusually cool under the cloudy skies, there was a high humidity to the air allowing visible water vapour to trail off the cars at high speed, giving a slight extra twist to the teams' headaches as they worked on their set-up and handling ahead of this afternoon's all-important qualifying session.

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Of the drivers who headed out on installation laps, only Marussia's Jules Bianchi and Toro Rosso's Daniel Ricciardo actually stayed out for a proper flying lap, Ricciardo going top with an initial lap of 1:42.450s that he soon carved almost two and a half seconds off in his next attempt, before finally cracking the 100-second mark with a time of 1:39.130s as his team mate Jean-Eric Vergne also joined him at the top of the timesheets.

Adrian Sutil hinted that Force India had got to grips with their Friday struggles by setting a new benchmark time of 1:38.559s 12 minutes into the session, and he went faster still to stay at the top until the Red Bulls went into action, Mark Webber topping the times first with a lap of 1:38.158s and then Sebastian Vettel taking control with a new target to beat of 1:37.433s a third of the way into the hour.

There was positive news at the other end of the timings as well, with Guido van der Garde telling his pit wall that he was much happier with the Caterham today compared with Friday's frustrating outings, commenting that "I can do whatever I want with it" now that the previous day's understeer was under control.

At the halfway point there had been some off-track excursions but no significant incidents and Vettel's time still stood at the top of the timesheets, with Nico Hulkenberg up into second place in the Sauber a third of a second behind, followed by Lotus' Romain Grosjean and McLaren's Jenson Button, with Webber having now slipped down to fifth place just ahead of Sergio Perez who was sixth on the hard compound Pirelli tyres.

Webber opted to experiment with a set-up change to the front torsion bars for his next run, which enabled him to move back up into second place in his next run but still 0.193s off his team mate who continued to hold the whip hand, and with no one else making any further progress on the prime tyres everyone duly returned to pit road with 15 minutes remaining in order to contemplate their final practice runs.

Bianchi was the first to leap back into action followed by a brace of McLarens. All three on medium options for the first time today which allowed Button to leap into second place with a new best time of the day for the McLaren of 1m37.621. The rest of the field also decided it was time to get some qualifying practice in on the options as they also rejoined the fray, with Hulkenberg finally able to break Vettel's hold at the top and set a new target time of 1:37.272s.

It proved a short-lived success however as the Red Bull pair immediately responded and trampled over the competition by going first and second again, Vettel's new time of 1:36.733s two tenths ahead of Webber with Lewis Hamilton slipping into third for Mercedes ahead of Hulkenberg in the dying seconds of the session.

Grosjean and Button ended up in fifth and sixth with Nico Rosberg in seventh just ahead of Perez who was the last man within a second of Vettel's laptime, and the remainder of the top ten filled out by Williams' Valtteri Bottas and by Force India's Adrian Sutil.

It was a disappointing and worrying session for Ferrari fans, with Fernando Alonso unable to crack the top ten and left 1.030s off Vettel's benchmark. Esetaban Gutierrez finished FP3 in 12th place a tenth of a second ahead of new Lotus driver Heikki Kovalainen, who ended up ahead of Pastor Maldonado, Daniel Ricciardo, Paul di Resta, Felipe Massa and Jean-Eric Vergne, with Charles Pic edging his team mate Giedo van der Garde out in the battle to be the best of the backmarker teams.

See full FP3 times.