Bagnaia - who was demoted from second to fifth due to a grid penalty - claimed the lead at Turn 2 on the opening lap and never looked back, taking the chequered flag by 0.8s over team-mate Bastianini, as championship leader Jorge Martin had to settle for third.
At the start of the race, Bagnaia made a brilliant launch from fifth on the grid, taking the outside line into Turn 1 to shoot up to second position, before sending his factory Ducati up the inside of Martin to snatch the lead.
Once in front, Bagnaia set a series of fastest laps to break away from Martin, although the Pramac rider was able to cut his deficit back to 0.6s at the halfway stage of the race.
