Pole-starter Marco Bezzecchi won India's inaugural MotoGP in a near-flawless race on Sunday, but world champion Francesco Bagnaia crashed out after slipping on a turn.
Jorge Martin, who won Saturday's sprint race, just held on for second spot with Fabio Quartararo a close third at the Buddh International Circuit.
Italy's Bezzecchi, on a Ducati-VR46, won his third race of the season in 36 minutes, 59.157 seconds and punched the air in celebration in front of a raucous grandstand.
But it was heartbreak for Bagnaia, who lost control of his Ducati and the bike went for a somersault.
The Italian still leads the world championship with 292 points but saw his lead cut in the 13th race of the 20-race season. Martin is on 279 points followed by Bezzecchi on 248.
"Wasn't easy for sure because of the heat and everything. But I felt good on the bike," Bezzecchi told reporters.
Bezzecchi crashed out in the first lap of Saturday's sprint race before finishing fifth and said the incident motivated him to come up trumps. "After yesterday I was really motivated to bounce back because I think, yesterday also I could have done a bit better than fifth," he said.