Marc Marquez led the way in the first practice session for the GP of the Americas at Austin, leading reigning MotoGP champion Jorge Lorenzo by a quarter of a second.
Honda rider Marquez, who has never lost a race at the Circuit of the Americas, topped the timesheets from the very start, and had 1.2 seconds over Lorenzo's factory Yamaha at the end of the opening runs.
He improved to a 2m04.953s at the start of his second run, which would remain unbeaten for the remainder of the session, as Ducati's Andrea Iannone took over as his closest rival with a time 0.617s adrift.
Lorenzo, however, managed to grab the runner-up spot back on his third and final run with only three minutes remaining on the clock, lapping within 0.255s of Marquez - who set two overall best sectors on his last lap but failed to improve.
That left Iannone, his Ducati running with large wings on the side of the fairing as well as at the front during the session, in third, ahead of Avintia Ducati rider Hector Barbera, who split the Italian marque's works machines on his final lap, 0.719s down on Marquez.
Andrea Dovizioso was demoted to fifth ahead of Pramac's Scott Redding, with Valentino Rossi lapping 1.3s off the pace in seventh on the second of the Yamahas.
Yonny Hernandez (Aspar Ducati), Maverick Vinales (Suzuki) and Marquez's Repsol Honda teammate Dani Pedrosa, who hoisted himself into 10th on his final lap, were next up.
The only crasher in a largely incident-free session was the Marc VDS Honda of Jack Miller, who suffered a major high-side at Turn 18.
He was taken to the medical centre to be evaluated, and was given a precautionary x-ray on his right ankle, but was declared fit and will take part in FP2 as scheduled.
|1||Marc Marquez||Repsol Honda Team||Honda RC213V||2:04.953||2:04.953|
|2||Jorge Lorenzo||Yamaha Factory Racing||Yamaha YZR-M1||2:05.208||+0.255|
|3||Andrea Iannone||Ducati Team||Ducati Desmosedici GP16||2:05.570||+0.617|
|4||Hector Barbera||Avintia Racing||Ducati Desmosedici GP14||2:05.682||+0.729|
|5||Andrea Dovizioso||Ducati Team||Ducati Desmosedici GP16||2:06.032||+1.079|
|6||Scott Redding||Octo Pramac Yakhnich||Ducati Desmosedici GP15||2:06.224||+1.271|
|7||Valentino Rossi||Yamaha Factory Racing||Yamaha YZR-M1||2:06.252||+1.299|
|8||Yonny Hernandez||Aspar Racing Team||Ducati Desmosedici GP14||2:06.264||+1.311|
|9||Maverick Viñales||Team Suzuki ECSTAR||Suzuki GSX-RR||2:06.367||+1.414|
|10||Dani Pedrosa||Repsol Honda Team||Honda RC213V||2:06.450||+1.497|
|11||Aleix Espargaro||Team Suzuki ECSTAR||Suzuki GSX-RR||2:06.482||+1.529|
|12||Pol Espargaro||Tech 3||Yamaha YZR-M1||2:06.581||+1.628|
|13||Cal Crutchlow||Team LCR||Honda RC213V||2:06.772||+1.819|
|14||Stefan Bradl||Aprilia Racing Team Gresini||Aprilia RS-GP||2:07.135||+2.182|
|15||Tito Rabat||Estrella Galicia 0,0 Marc VDS||Honda RC213V||2:07.189||+2.236|
|16||Bradley Smith||Tech 3||Yamaha YZR-M1||2:07.259||+2.306|
|17||Eugene Laverty||Aspar Racing Team||Ducati Desmosedici GP14||2:07.261||+2.308|
|18||Alvaro Bautista||Aprilia Racing Team Gresini||Aprilia RS-GP||2:07.449||+2.496|
|19||Loris Baz||Avintia Racing||Ducati Desmosedici GP14||2:07.506||+2.553|
|20||Michele Pirro||Octo Pramac Yakhnich||Ducati Desmosedici GP15||2:07.895||+2.942|
|21||Jack Miller||Estrella Galicia 0,0 Marc VDS||Honda RC213V||2:07.897||+2.944|