Leopard Racing Honda rider Danny Kent continued his domination at the Circuit of the Americas to take his first victory of 2015 by 8.532secs on a drying track which caught out many of the top riders.
A poor start saw Kent down in sixth position, but the 21-year-old Brit didn't panic and carefully picked his way through the lead group until he was at the front and able to gap the chasing pack.
While Kent cruised to victory, it was all action in the battle for the final podium positions, with multiple overtakes and crashes throughout the race.
Factory KTM rider and early race leader Miguel Oliveira, Nicollo Antonelli, Jorge Navarro and Francesco Bagnaia all fell while battling for second position.
Alexis Masbou, race winner last time out at Qatar, crashed out of fifth place on the final corner and pushed his bike over the line to no avail, crossing the line in 16th out of the points.
Masbou's crash handed fifth place to Brad Binder - the highest non-Honda - with John McPhee close behind in sixth.
1. Danny Kent GBR Leopard Racing (Honda) 41m 32.287s
2. Fabio Quartararo FRA Estrella Galicia 0,0 (Honda) 41m 40.819s
3. Efren Vazquez SPA Leopard Racing (Honda) 41m 40.939s
4. Enea Bastianini ITA Gresini Racing Team Moto3 (Honda) 41m 41.098s
5. Brad Binder RSA Red Bull KTM Ajo (KTM) 41m 41.843s
6. John Mcphee GBR SAXOPRINT RTG (Honda) 41m 46.156s
7. Andrea Locatelli ITA Gresini Racing Team Moto3 (Honda) 41m 52.729s
8. Romano Fenati ITA SKY Racing Team VR46 (KTM) 41m 52.898s
9. Isaac Viñales SPA Husqvarna Factory Laglisse (Husqvarna) 41m 53.150s
10. Karel Hanika CZE Red Bull KTM Ajo (KTM) 41m 53.200s
11. Jakub Kornfeil CZE Drive M7 SIC (KTM) 41m 53.536s
12. Andrea Migno ITA SKY Racing Team VR46 (KTM) 41m 56.012s
13. Philipp Oettl GER Schedl GP Racing (KTM) 42m 4.505s
14. Niklas Ajo FIN RBA Racing Team (KTM) 42m 8.989s
15. Matteo Ferrari ITA San Carlo Team Italia (Mahindra) 42m 9.570s
16. Alexis Masbou FRA SAXOPRINT RTG (Honda) 42m 19.314s
17. Maria Herrera SPA Husqvarna Factory Laglisse (Husqvarna) 42m 31.544s
18. Remy Gardner AUS CIP (Mahindra) 42m 36.035s
19. Gabriel Rodrigo ARG RBA Racing Team (KTM) 42m 36.898s
20. Zulfahmi Khairuddin MAL Drive M7 SIC (KTM) 42m 49.255s
21. Alessandro Tonucci ITA Outox Reset Drink Team (Mahindra) 42m 59.684s
22. Ana Carrasco SPA RBA Racing Team (KTM) 43m 12.696s
23. Niccolò Antonelli ITA Ongetta-Rivacold (Honda) 43m 16.128s
24. Stefano Manzi ITA San Carlo Team Italia (Mahindra) 43m 18.392s
25. Livio Loi BEL RW Racing GP (Honda) +1 lap
Tatsuki Suzuki JPN CIP (Mahindra) DNF
Miguel Oliveira POR Red Bull KTM Ajo (KTM) DNF
Francesco Bagnaia ITA MAPFRE Team MAHINDRA (Mahindra) DNF
Jorge Navarro SPA Estrella Galicia 0,0 (Honda) DNF
Jorge Martin SPA MAPFRE Team MAHINDRA (Mahindra) DNF
Hiroki Ono JPN Leopard Racing (Honda) DNF
Jules Danilo FRA Ongetta-Rivacold (Honda) DNF
Darryn Binder RSA Outox Reset Drink Team (Mahindra) DNF
Juanfran Guevara SPA MAPFRE Team MAHINDRA (Mahindra) DNF
15-year-old Frenchman Fabio Quartararo crossed the line in second position, ahead of Kent's team-mate Efren Vasquez/