BURIRAM (Thailand) • Marc Marquez sealed his sixth MotoGP world title in Thailand yesterday after a heart-pounding final corner duel with Fabio Quartararo, but said it had not been an "easy" year as the front runner.

Honda's Marquez, who passed the French Yamaha rider on the last lap after a wheel-to-wheel duel in the sweltering heat, now has an unsurpassable 325 points over closest rival Andrea Dovizioso's 215 with four races left in the season.

It is also Marquez's fourth championship in a row.

The Spaniard, who had a huge crash in Friday practice that sent him to hospital for checks and then fell again in qualifying, did not put a wheel wrong as he reined in pole-sitter Quartararo and denied the 20-year-old rookie a first win.

The pair were just 0.171sec apart at the line with another Spanish Yamaha rider Maverick Vinales third 1.38sec back at Buriram's Chang International Circuit. Italian Ducati rival Dovizioso finished a distant fourth.

Marquez, 26, jumped up and down with joy after the victory and was handed a large eight-ball to signify the eight overall championships across all classes he has won. He is the youngest rider to win so many. He was 125cc (now Moto3) world champion in 2010 and Moto2 winner in 2012.

Starting from third on the grid, Marquez quickly slipped by Vinales and spent most of the race trying to overcome Quartararo.

The Frenchman held the lead through 25 of the 26 laps but Marquez made his move on the final circuit, flying past the leader as the crowd screamed in delight.

A relieved-looking Marquez said it was now "time to enjoy" after a high-pressure season with many competitors clamouring to topple the reigning champion. He said: "Everybody is looking to beat you, it's not easy."

He also described the 2019 season as his best in MotoGP.

With six premier class titles, the Honda superstar moves past Australian legend Mick Doohan and trails only Italian great Valentino Rossi, who won the last of his seven championships in 2009, and Giacomo Agostini, whose record eight came between 1966 and 1975.

But Quartararo is fast emerging as one of Marquez's toughest rivals.

"I didn't expect this guy," he said of the youngster, calling him "the outsider". "He will be a very tough contender next year for the championship."

Quartararo admitted he was "really frustrated" at losing in such a close fight to the finish but recognised that it was a great result considering who he was up against.

"We tried until the last corner," he said after his fifth 2019 podium.

Marquez has won nine races this season, including the last three in a row, with 14 podium finishes.

Italy's Luca Marini won the Moto2 title, while Albert Arenas from Spain grabbed the Moto3 victory.

AGENCE FRANCE-PRESSE, REUTERS