Reigning Moto3 world champion Maverick Vinales has taken his first Moto2 victory at only his second attempt after passing Dominique Aegerter for the lead with six laps to go in Austin.

Vinales then bolted, while Qatar winner Esteve Rabat lost time getting around Aegerter for second place. Xavier Simeon, who had been leading until a sideways braking moment with seven to go, fell while trying to take third from Aegerter on the penultimate lap.

The start was delayed due to spots of rain, but the race remained classified as 'dry' with slick tyres used by all.

A first turn incident triggered by home rookie Josh Herrin resulted in Mattia Pasini, Sam Lowes, Jordi Torres and Franco Morbidelli also ending up on the ground.

Herrin's Caterham team-mate Johann Zarco then wiped out Julian Simon from the lead group several laps later...

1.Maverick Vi?alesSPA Pons HP 40 (Kalex)41m 31.520s
2.Esteve RabatSPA Marc VDS Racing Team (Kalex)41m 35.529s
3.Dominique AegerterSWI Technomag carXpert (Suter)41m 38.843s
4.Mika KallioFIN Marc VDS Racing Team (Kalex)41m 40.110s
5.Simone CorsiITA NGM Forward Racing (Forward KLX)41m 41.454s
6.Thomas LuthiSWI Interwetten Paddock Moto2 (Suter)41m 48.507s
7.Anthony WestAUS QMMF Racing Team (Speed Up)41m 49.081s
8.Alex De AngelisRSM Tasca Racing Moto2 (Suter)41m 50.468s
9.Marcel SchrotterGER Tech 3 (Tech 3)41m 51.240s
10.Ricard CardusSPA Tech 3 (Tech 3)41m 56.072s
11.Takaaki NakagamiJPN IDEMITSU Honda Team Asia (Kalex)41m 59.983s
12.Mattia PasiniITA NGM Forward Racing (Forward KLX)42m 15.475s
13.Randy KrummenacheSWI IodaRacing Project (Suter)42m 15.864s
14.Sandro CorteseGER Dynavolt Intact GP (Kalex)42m 17.186s
15.Hafizh SyahrinMAL Petronas Raceline Malaysia (Kalex)42m 20.811s
16.Sam LowesGBR Speed Up (Speed Up)42m 22.674s
17.Franco MorbidelliITA Italtrans Racing Team (Kalex)42m 22.851s
18.Azlan ShahMAL IDEMITSU Honda Team Asia (Kalex)42m 23.203s
19.Axel PonsSPA AGR Team (Kalex)42m 23.633s
20.Tetsuta NagashimaJPN Teluru Team JiR Webike (TSR)42m 33.623s
21.Roman RamosSPA QMMF Racing Team (Speed Up)42m 33.866s
22.Thitipong WarokornTHA APH PTT The Pizza SAG (Kalex)42m 35.015s
23.Julian SimonSPA Italtrans Racing Team (Kalex)42m 36.464s
24.Robin MulhauserSWI Technomag carXpert (Suter)42m 41.461s
25.Gino ReaGBR AGT REA Racing (Suter)42m 51.850s
26.Jordi TorresSPA Mapfre Aspar Team Moto2 (Suter)43m 5.301s