VR46 Ducati's Luca Marini grabbed the top spot in first practice for Round 3 of the MotoGP World Championship at the Circuit of the Americas in Texas.
Marini set the fastest time on his Desmosedici in 2'03:250s to head the timesheets by 0.150s from Frenchman Fabio Quartararo, who had led the way earlier in the session on the Monster Energy Yamaha after fitting a new medium rear tyre.
Johann Zarco climbed to third on the Pramac Ducati, just over a further tenth behind, with Alex Marquez (Gresini Ducati) slotting into fourth.
Zarco's Pramac Ducati team-mate Jorge Martin completed the top six ahead of reigning champion Francesco Bagnaia (Lenovo Ducati) and Maverick Viñales (RNF Aprilia), with the top eight covered by just over six tenths of a second.
Takaaki Nakagami (LCR Honda) and Brad Binder (Red Bull KTM) rounded out the first 10.
Championship leader Marco Bezzecchi ended FP1 in 13th position on the VR46 Ducati after crashing at Turn 12 towards the end.
The returning Miguel Oliveira was 15th on the RNF Aprilia as the Portuguese makes his comeback after being wiped out by Repsol Honda's Marc Marquez in the season-opener at Portimao in Portugal in March.
Michele Pirro, one of Ducati's test riders, was 21st as he stands in for the injured Enea Bastianini this weekend in the factory squad, while fellow test rider Jonas Folger brought up the rear of the field on the GASGAS Tech3 KTM.
Folger, set to compete in his first MotoGP race since 2017, was black-flagged at the start of the session, with smoke belching from the rear of his machine.
Folger was called into the team for Round 3 as Pol Espargaro continues to recover from back, jaw and lung injuries sustained in a nasty crash in free practice in Portugal.