PHILLIP ISLAND, Australia (AP) — Marc Marquez took a giant step toward retaining his MotoGP world title when he won the Australian Grand Prix Sunday, extending his championship lead to 33 points with just two rounds remaining.

Starting from pole position, the Spanish Honda rider took the race lead with seven laps remaining, then accelerated away from the field to win comfortably by 1.8 seconds from Italy's Valentino Rossi and his Yamaha teammate Maverick Vinales.

Marquez's only remaining rival for the world championship, Italian rider Andrea Dovizioso, finished 13th on his Ducati to see his title hopes all but evaporate.

Already a three-time MotoGP champion, Marquez, 24, has now won six races this season and can clinch his fourth world title with a top-two finish in either of the remaining two races.

"Amazing, amazing. I knew before the race that today was an important day," said Marquez, who crashed out while leading last year's Australian MotoGP.

"I was feeling really good and during the race I was just waiting, waiting, waiting and then in the last few laps I give all-in.

"I pushed really hard for three or four laps. The fight was amazing."

Rossi timed his run to perfection to finish second after a dogged battle with Vinales and Johann Zarco for the other podium positions.

"I enjoyed the race very much," Rossi said. "This track is unbelievable and it was a great, great race.

"All the riders in front are very aggressive so you needed to be more stupid than them, more aggressive.

"I wanted to try for the podium at the maximum and the end with second place I'm very happy."

Joan Mir was earlier crowned world champion in the Moto3 class when he won his rain-shortened race.

The race was stopped with seven laps remaining because of heavy rain with the 20-year-old Spaniard in the lead.

With his ninth victory of the season, Mir has an unassailable 70-point lead over his nearest rival, Italy's Romano Fenat, with a maximum 50 points available from the last two races.

"It's unbelievable ... I've dreamt about this for a lot of years," Mir said. "I've worked really hard for this and now to achieve it is amazing.

"I'm a world champion — it's incredible to say."

Mir's teammate Livio Loi finished second while Jorge Martin was third after starting from pole position.

Italy's Franco Morbidelli stretched his lead in the Moto2 championship to 29 points after finishing third in Sunday's Moto2 race.

Portugal's Miguel Oliveira grabbed his first win in the class, crossing the line ahead of South African rookie Brad Binder just as the weather started to turn foul.

"With three laps to go it started raining and I had a six seconds lead then I was too cautious and the gap was reduced," Oliveiri said. "I stressed a little bit. It was the longest race of my life but I'm so happy for my team."

Switzerland's Thomas Luthi, who is second in the championship standings, lost slipped even further behind Morbidelli when he finished 10th.

"I wanted to get a podium to I was pushing really hard because I had to get this one," Morbidelli said. "It's great for the championship."