Sebastian Vettel said he was pleased with the opening day of running at the Circuit of the Americas despite losing time on track to a water leak.
The F1 points leader blitzed the field to top the opening practice session by more than a second, but his second session looked set to end early when he was forced to return to the pits after just a handful of laps.
Red Bull were however able to get the German back on track for the final half hour and he duly set the pace once again, ending FP2 seven-tenths clear of his closest challenger.
“It was slippery this morning and a bit like driving on ice,” he said. “It wasn't so easy, but we managed to get into a rhythm. We had a bit of a problem this afternoon and so couldn't run as much as we wanted, but we got two good runs which is important for tomorrow and Sunday.
“I think there were a couple of surprises today in terms of pace, so we'll see tomorrow. The track will constantly improve – it's good that we are amongst the guys at the top, now we'll try to improve the car to make sure we stay there.”
Vettel's closest challenger on the times turned out to be team-mate Mark Webber, with the Australian pleased to have been able to get into a 'good rhythm' as drivers worked to learn the new venue.
“It's a pretty good track, it's quick, especially the first sector which is quite full on, although sectors two and three are more traditional and similar to other tracks,” he said. “It was very slippery to start with, which was quite frustrating probably for all of us, but in the end the track rubbered in pretty well and we got into a good rhythm.
“As with all new circuits, you've got to work out where you can prioritise your time and where to compromise. It's got a bit of everything really, so it's good.”