LCR Honda's Stefan Bradl underscored Honda's day one dominance in Austin as the German rider completed an RC213V clean sweep of the top three positions.
Ninth in the morning session, the former Moto2 world champion headed the times in the afternoon before slipping behind the factory pair of Marc Marquez and Dani Pedrosa.
Bradl's quickest time of 2m 06.173s left him 1.142s adrift of the flying Marquez and half a second down on Pedrosa as he completed the day in third place on the time sheets.
He struggled with poor grip in FP1 but hit his stride in the afternoon and Bradl will be hoping to use the apparent superiority of the Honda machines at the Circuit of the Americas to his advantage this weekend.
“Today has been a strange day for us,” said Bradl, who took part in last month's private test at the circuit.
“This morning the track conditions were pretty bad and the grip level was very poor so we could not use our advantage from the test.
“At the end of this morning first session, I was very disappointed but, in the afternoon, the grip was much better and the sun was shining so I could ride a lot faster keeping the top positions,” he added.
“We could use the data and the references obtained in the test but we still have to adjust the race set-up especially when we are on used tyres.”