Dani Pedrosa closed the gap on championship leader Jorge Lorenzo by winning the Indianapolis MotoGP.
The Repsol Honda rider, who had started on pole, took the race ahead of Lorenzo to move to within 18 points of his Spanish compatriot in the standings.
Andrea Dovizioso came third while Casey Stoner, taking part despite having suffered multiple injuries in a crash in qualifying, finished fourth.
Britain's Cal Crutchlow crashed out from seventh.
"It was a very good race. The bike was working perfectly. I had good pace and I am very pleased with that," Pedrosa said.
"I am so happy with this win."
It was ultimately a comfortable victory for the 26-year-old, who crossed the finish line more than 10 seconds ahead of Lorenzo.
However, he did benefit from some misfortune for Ben Spies.
The home favourite had made a superb start to climb into the lead at the second corner.
But disaster struck just six laps in for the American as white smoke suddenly started pluming out of his engine, forcing him to retire with mechanical problems.
"We got a good start but then I could feel the bike tighten up and then it just went," said Spies. "I started slowing down to get off the line because I could see there was a lot of smoke.
"It is another one of those weekends."
Alvaro Bautista finished fifth with Stefan Bradl sixth.
Valentino Rossi came home seventh, a position Crutchlow had held before crashing out at Turn Four early on.
It is the first time this year Crutchlow has failed to score points.
"I lost the front. We have been struggling all weekend and it is disappointing, it was the first race we have not finished this year," he said.
"We have to go away and have a look at it and see where we need to improve for next weekend."
Cardion AB's Karel Abraham took eighth with Avintia Blusens's Yonny Hernandez coming out on top of a battle with Aspar's Aleix Espargaro for ninth.
In Moto2, Marc Marquez claimed a fifth race victory of the season with a dominant display to extend his championship lead to 39 points.
Marquez finished 5.9 seconds clear of title rival Pol Espargaro, while Julian Simon crossed the line in third place.
Finally, Luis Salom won his first Moto3 race as he surged past championship leaders Sandro Cortese and Maverick Vinales on the last lap to secure victory. Cortese took second and Jonas Folger came third after Vinales crashed out at the final turn.
Indianapolis Grand Prix results:
1. Dani Pedrosa (Spa) Repsol Honda 46:39.631
2. Jorge Lorenzo (Spa) Yamaha 46:50.454
3. Andrea Dovizioso (Ita) Tech 3 Yamaha 46:56.941
4. Casey Stoner (Aus) Repsol Honda 46:59.434
5. Alvaro Bautista (Spa) Gresini Honda 47:02.187
6. Stefan Bradl (Ger) LCR Honda 47:09.703
7. Valentino Rossi (Ita) Ducati 47:37.245
8. Karel Abraham (Cze) Cardion AB 47:48.073
9. Yonny Hernandez (Col) Avintia Bluesens 47:50.737
10. Aleix Espargaro (Spa) Aspar 47:53.710
1. Jorge Lorenzo 225 points
2. Dani Pedrosa 207 points
3. Casey Stoner 186 points
4. Andrea Dovizioso 137 points
5. Cal Crutchlow 106 points