Great start
Vinales got off to a great start from the middle of the front row and grabbed the holeshot into Turn 1, with Miller getting his Ducati off the line like a rocket to initially go P2.
The Australian was wide though which let Marquez come through into second after a fairly average getaway, with pole-sitter Quartararo slotting into P3 at Turn 2 as he then got the better of Miller.
Toe-to-toe
However, the Desmosedici grunt saw Miller get up the inside of Quartararo down into the Dani Pedrosa corner, as Vinales got out the seat around Turn 8 in an early scare for the number 12.
Francesco Bagnaia (Pramac Racing) was then past Quartararo on Lap 2 as the Frenchman initially fell back, but he was back through at the final corner on that lap as Marquez and Vinales went toe-to-toe at Turn 4, before Marquez managed to make the move stick at Dani Pedrosa corner.
Another twist
Coming across the line with four laps remaining, Marquez was plotting his move into P2. However, there was about to be another twist - and a vast one at that.
Coming out of Turn 3, Marquez was launched off his RC213V in a vicious way. Tumbling heavily through the gravel, the reigning champion was taken to the medical centre - and has a broken right humerus, for which he needs a surgery.
Battle for podium
Back at the front, Quartararo crossed the line to take an incredible maiden MotoGP victory, making some history and converting some searing premier class pace into a winner's trophy.
Vinales took P2 from Dovizioso, with Miller leading Morbidelli and Espargaro over the line. P2-P6 were covered by just 2.3sec.