Vettel completes USA practice sweep

Sebastian Vettel goes into United States Grand Prix qualifying as a strong pole favourite after completing a clean sweep of fastest practice times on Saturday morning at Austin.

As had been the case in both Friday sessions, when Vettel unleashed the Red Bull's pace, he blasted the rest of the field away, although Lewis Hamilton eventually narrowed the gap to 0.258 seconds.

The Red Bull's ability to get its tyres working in the chilly morning temperatures appeared to be key.

Many drivers found that they could not generate any tyre temperature in time when they moved onto the medium Pirellis in the final minutes.

Vettel was a spectacular exception, as he swiftly delivered a 1m36.490s.

Others needed several more laps to improve on their hard tyre times, with Hamilton finally making it to a 1m36.748s. The McLarens had been first and second on hard tyre pace earlier in the session.

Pastor Maldonado fared better than many with the tyres and got his Williams to second for a spell before Hamilton slipped ahead.

Fernando Alonso's first medium tyre run saw his Ferrari slew wildly off the road at Turn 19. He eventually got to fourth, with team-mate Felipe Massa behind Nico Rosberg's Mercedes in sixth.

Mark Webber, Sergio Perez, Nico Hulkenberg and Jenson Button completed the top 10.

Two drivers ended the session on the sidelines. Jean-Eric Vergne parked his Toro Rosso trackside with broken suspension, while compatriot Romain Grosjean got no mileage on the medium tyres as a gearbox issue kept his Lotus in the garage.

After Friday's clash between Vergne and Heikki Kovalainen, drivers continued to trip over each other during practice three.

Michael Schumacher and Massa had a near miss at the penultimate corner, and Perez and Charles Pic made contact at Turn 7 as the Sauber tried to dive past the Marussia, which was shoved into a spin. Both Perez and Pic were summoned to the stewards after the session.