Honda's Marc Marquez set the fastest lap time in Friday's first practice session for this weekend's Grand Prix of the Americas.
Marquez has won all three races at the the Circuit of the Americas since its introduction to the MotoGP calendar in 2013, and once again looked in great form as he set the early pace with a lap time of 2m04.953s.
Ducati's Andrea Iannone was in second place for most of the day, 0.617 behind Marquez, but reigning world champion Jorge Lorenzo managed to get within 0.255s of the leader in the closing minutes of the session.
Iannone held on to third, leading a group of four Ducatis which included Hector Barbera (fourth), Andrea Dovizioso (fifth) and Scott Redding (sixth).
Following last week's problems with with Scott Redding's Pramac Ducati in Argentina, riders opted for new soft and medium Michelin rear tyres, which only went into production in France on Monday.
Valentino Rossi could only manage seventh, although he tried out the 'alternative version' of Yamaha's YZR-M1 for the first time since pre-season testing in February.
Jack Miller was flung off his Marc VDS Honda at Turn 18, but x-rays revealed no serious damage.
Free Practice 1 results
1. Marc Marquez ESP Repsol Honda Team (RC213V) 2m 04.953s [Lap 10/17] 339km/h (Top Speed)
2. Jorge Lorenzo ESP Movistar Yamaha MotoGP (YZR-M1) 2m 05.208s 0.255s [13/15] 338km/h
3. Andrea Iannone ITA Ducati Team (Desmosedici GP) 2m 05.570s 0.617s [9/14] 344km/h
4. Hector Barbera ESP Avintia Racing (Desmosedici GP14.2) 2m 05.682s 0.729s [15/15] 338km/h
5. Andrea Dovizioso ITA Ducati Team (Desmosedici GP) 2m 06.032s 1.079s [9/14] 345km/h
6. Scott Redding GBR Octo Pramac Yakhnich (Desmosedici GP15) 2m 06.224s 1.271s [14/16] 341km/h
7. Valentino Rossi ITA Movistar Yamaha MotoGP (YZR-M1) 2m 06.252s 1.299s [16/16] 339km/h
8. Yonny Hernandez COL Aspar MotoGP Team (Desmosedici GP14.2) 2m 06.264s 1.311s [13/13] 340km/h
9. Maverick Viñales ESP Team Suzuki Ecstar (GSX-RR) 2m 06.367s 1.414s [13/15] 341km/h
10. Dani Pedrosa ESP Repsol Honda Team (RC213V) 2m 06.450s 1.497s [16/16] 341km/h
11. Aleix Espargaro ESP Team Suzuki Ecstar (GSX-RR) 2m 06.482s 1.529s [12/13] 336km/h
12. Pol Espargaro ESP Monster Yamaha Tech 3 (YZR-M1) 2m 06.581s 1.628s [9/16] 340km/h
13. Cal Crutchlow GBR LCR Honda (RC213V) 2m 06.772s 1.819s [11/15] 338km/h
14. Stefan Bradl GER Factory Aprilia Gresini (RS-GP) 2m 07.135s 2.182s [14/14] 334km/h
15. Tito Rabat ESP Estrella Galicia 0,0 Marc VDS (RC213V)* 2m 07.189s 2.236s [17/18] 336km/h
16. Bradley Smith GBR Monster Yamaha Tech 3 (YZR-M1) 2m 07.259s 2.306s [11/13] 339km/h
17. Eugene Laverty IRL Aspar MotoGP Team (Desmosedici GP14.2) 2m 07.261s 2.308s [15/15] 343km/h
18. Alvaro Bautista ESP Factory Aprilia Gresini (RS-GP) 2m 07.449s 2.496s [15/16] 336km/h
19. Loris Baz FRA Avintia Racing (Desmosedici GP14.2) 2m 07.506s 2.553s [14/14] 335km/h
20. Michele Pirro ITA Octo Pramac Yakhnich (Desmosedici GP15) 2m 07.895s 2.942s [9/13] 338km/h
21. Jack Miller AUS Estrella Galicia 0,0 Marc VDS (RC213V) 2m 07.897s 2.944s [5/7] 339km/h