Reigning MotoGP champion Marc Marquez was victorious in the Australian Grand Prix as long-time race leader Maverick Vinales crashed out on the final lap.
Both Marquez and Vinales started from the front row but had slow getaways, meaning Valentino Rossi - making his 400th MotoGP start - held the lead, with Cal Crutchlow and Andrea Iannone completing an unusual early top three behind the Yamaha rider.
Fabio Quartararo's attempts to score a maiden MotoGP victory ended after just two corners when he went wide at Southern Loop and found himself in exactly the wrong spot to be hit by the high-siding Danilo Petrucci behind him.
Rossi held the lead for three laps before Crutchlow passed him, and they Yamaha rider then lost several positions in quick succession, dropping as low as seventh.
Iannone put his Aprilia in the lead with a move at Turn 10, but Crutchlow slipstreamed back ahead of him on the main straight.
The Briton cemented his lead for the next few laps while Iannone duelled with Marquez before Vinales, recovering from a slow start, overtook both in quick succession, and then passed Crutchlow at Turn 4 on lap 10.
Marquez barged past Crutchlow at Lukey Heights in order to stay with Vinales, and from there the top two quickly pulled away from the chasing pack.
Marquez shadowed Vinales for the remaining 17 laps of the race, with the gap between the two less than a tenth each time they crossed the line in the final stages, before the Honda rider pounced on the final lap - slipstreaming past Vinales on the main straight then holding off the Yamaha rider at Turn 4.
Vinales lined up a move at Turn 10, where he had earlier passed Marquez, but he crashed as he exited Lukey Heights - leaving Marquez to take the chequered flag on his own.
That victory was his 11th of the season and his fifth in a row, while Marquez also surpassed 500cc legend Mick Doohan to become Honda's most successful premier-class rider in terms of wins.
Crutchlow inherited second to complete a Honda 1-2, his best result of 2019, finishing 11.4 seconds behind Marquez.
Vinales's crash gifted Jack Miller a podium finish on home soil as he beat his Pramac team-mate Francesco Bagnaia by half a tenth.
Bagnaia, like fellow rookie Joan Mir behind him, celebrated the best result of his rookie season.
Iannone faded after his early race heroics but still secured sixth, beating Andrea Dovizioso's Ducati by just 0.014s, while Rossi ended up eighth.
Alex Rins was a disappointing ninth despite running fourth at one point, while the top 10 was completed by the second Aprilia of Aleix Espargaro.
Johann Zarco finished 13th on his first outing with the LCR Honda squad while Jorge Lorenzo finished dead last in 16th, more than a minute behind his team-mate Marquez.
Result - 27 laps
|2||Cal Crutchlow||LCR Honda||Honda||11.413s|
|3||Jack Miller||Pramac Ducati||Ducati||14.499s|
|4||Francesco Bagnaia||Pramac Ducati||Ducati||14.554s|
|11||Franco Morbidelli||Petronas Yamaha||Yamaha||24.145s|
|13||Johann Zarco||LCR Honda||Honda||26.758s|
|14||Karel Abraham||Avintia Ducati||Ducati||44.912s|
|15||Hafizh Syahrin||Tech3 KTM||KTM||44.968s|
|-||Tito Rabat||Avintia Ducati||Ducati||Retirement|
|-||Miguel Oliveira||Tech3 KTM||KTM||Withdrawn|
|-||Fabio Quartararo||Petronas Yamaha||Yamaha||Retirement|