Sebastian Vettel was fastest in both FP1 and FP2 in Austin despite sitting out of much of FP2 with a water leak on his Red Bull.
Vettel had only completed three laps when he was forced to return to the pits and would not return to the track for an hour.
Vettel’s teammate Mark Webber was second fastest in the second session ahead of Vettel’s championship rival Fernando Alonso in third.
Alonso will be hoping that he will be closer to Vettel in qualifying and the race in order to give himself the best chance of beating Vettel to the championship.
McLaren teammates Lewis Hamilton and Jenson Button finished the second session in fourth and fifth despite Hamilton having a spin.
Felipe Massa was sixth in the second Ferrari ahead of Nico Rosberg in seventh. Bruno Senna’s weekend began positively with the eighth fastest time in the second session ahead of Kamui Kobayashi in ninth.
Michael Schumacher completed the top ten ahead of Abu Dhabi winner Kimi Raikkonen in 11th.
Pastor Maldonado finished the session 12th in the second Williams whilst Romain Grosjean spun at turn one on his way to setting the 13th fastest time.
Behind them Sergio Perez could only manage 14th ahead of the two Toro Rossos. Force India could not replicate their FP1 form and only set the 17th and 18th fastest times.
At the back of the field finished Heikki Kovalainen, Timo Glock, Vitaly Petrov and Charles Pic ahead of the two HRTs.
Vettel’s impressive form in Austin despite problems with his car suggests that winning his third consecutive title is becoming more and more likely. Red Bull and Vettel are beginning to look as if they could walk away with the title if Alonso and Ferrari cannot produce something short of a miracle this weekend.