Michael Schumacher has revealed that two separate tyre issues put paid to any chance he had of charging up the timesheets in Austin.
Putting in the laps around the Circuit of the Americas track, Schumacher finished with a 1:40.115, which was over two seconds down on pace-setter Sebastian Vettel and six-tenths short of his own team-mate Nico Rosberg.
However, the German's day was not without problems as he suffered two tyre issues.
"We had a bit of a difficulty because we lost both sets of tyres for us; one delaminated and one had a puncture," he told ESPNF1.
"So we only had the tyres that we finally ran on from this morning. Obviously that compromised as well our session to work the car so we will have to see what it means."
As for the new track, Schumacher was complimentary although said the blind corners, such as Turn One, did come as a "shock" the first few laps.
"The track is pretty much a challenge, a nice layout and very interesting.
"It's very different sitting in a Formula One car compared to when you walk around or go with scooter, simply for the fact that you are sitting low in an F1 car and the vision is compromised.
"That was a bit of a shock the first lap out, but once you get into the track and you know where the corners are and how they are it's better, but still it remains a challenge."