Honda's Marc Marquez led the way in first practice for the third round of the MotoGP season at Austin.
Unbeaten at the Circuit of the Americas since it joined the MotoGP calendar in 2013, Marquez controlled top spot.
He set the early pace with a 2m05.435s lap, then improved to a 2m04.953s to lead the way into the final minutes, 0.617 seconds ahead of Andrea Iannone.
World champion Jorge Lorenzo closed to within 0.255s of Marquez with three minutes to go, with a time of 2m05.208s, but that was as close as anybody got.
Marquez was on a faster lap as the chequered flag flew, but lost time in the third and fourth sectors after catching Suzuki's Maverick Vinales, who wound up ninth.
Riders sampled new soft and medium Michelin rear tyres, with a stiffer construction but slightly softer compounds following last week's issue with Scott Redding's Pramac Ducati in Argentina.
The tyres went into production in France on Monday, and the softs were flown to Austin in time for the start of practice, with the mediums to follow on Saturday.
Iannone ended up third, leading a group of four Ducatis, followed by Hector Barbera, Andrea Dovizioso and Redding, who was among the riders to endure a 60-hour-plus trip from Termas de Rio Hondo due to a cancelled flight.
Valentino Rossi was seventh, but did try the 'alternative version' of Yamaha's YZR-M1 again for the first time since pre-season testing at Phillip Island in February.
Yonny Hernandez was eighth, ahead of Vinales and Dani Pedrosa, who Hernandez nearly cleaned up when he overshot braking into Turn 13.
Jack Miller was thrown from his Marc VDS Honda during a vicious highside at Turn 18, just after the halfway mark of the session.
He was taken to the medical centre, but an x-ray on his right foot confirmed the Australian did not break anything in the leg in which he fractured the tibia and fibula in January.
PRACTICE ONE TIMES
|4||Hector Barbera||Avintia Ducati||Ducati||2m05.682s||0.729s||15|
|6||Scott Redding||Pramac Ducati||Ducati||2m06.224s||1.271s||16|
|8||Yonny Hernandez||Aspar Ducati||Ducati||2m06.264s||1.311s||13|
|12||Pol Espargaro||Tech3 Yamaha||Yamaha||2m06.581s||1.628s||16|
|13||Cal Crutchlow||LCR Honda||Honda||2m06.772s||1.819s||15|
|15||Tito Rabat||Marc VDS Honda||Honda||2m07.189s||2.236s||18|
|16||Bradley Smith||Tech3 Yamaha||Yamaha||2m07.259s||2.306s||13|
|17||Eugene Laverty||Aspar Ducati||Ducati||2m07.261s||2.308s||15|
|19||Loris Baz||Avintia Ducati||Ducati||2m07.506s||2.553s||14|
|20||Michele Pirro||Pramac Ducati||Ducati||2m07.895s||2.942s||13|
|21||Jack Miller||Marc VDS Honda||Honda||2m07.897s||2.944s||7|