World champion Marc Marquez has won his ninth race of the MotoGP season in Malaysia, with Italian great Valentino Rossi crashing out four laps from the finish while leading.
Last month in Japan, Marquez wrapped up his fifth world title with three races to spare, but looked like having to settle for second in front of almost 104,000 fans on Sunday at the Sepang International Circuit.
Seven-time world champion Rossi - not winning since 26 races ago in Assen - had streaked past pole-sitter Johann Zarco at the start and led by seven-tenths of a second when his bike came out from under him on turn one.
Marquez, who had topped the times in qualifying but was relegated six places on the grid for impeding Suzuki's Andrea Iannone, safely negotiated the remaining four laps to secure his 44th MotoGP win.
The Spaniard's victory in 40 minutes 32.372 seconds also wrapped up the constructors' championship for Honda for the fourth-straight year with one round of the season remaining.
"I was pushing hard and starting to catch Vale but, when I saw his mistake, then I cooled down and just finished the race," said Marquez.
"It was the best way to celebrate the championship."
Alex Rins finished second for Suzuki ahead of Yamaha rider Zarco, with Rossi's teammate Maverick Vinales, who gave Yamaha a first win of the year last week in Australia, a creditable fourth after starting 11th on the grid.
Italian Andrea Dovizioso was sixth behind Honda's Dani Pedrosa to ensure a second-placed finish in the championship ahead of Rossi, who crossed the line in 18th.
Hafizh Syahrin, who became the first Malaysian rider to compete this season in MotoGP , was 10th on his Yamaha despite starting at the back of the grid.
Earlier, both junior titles were decided with Italian Pecco Bagnaia sealing the Moto2 world championship for the Sky Racing VR46 team by finishing third, as his teammate Luca Marini, team owner Rossi's half-brother, claimed a maiden victory.
Spain's Jorge Martin secured the Moto3 title with his seventh win of a season he had dominated for Honda.
