Ducati's Jack Miller claimed his first win of the season with a surprise blistering display at the Japanese Grand Prix in Motegi on Sunday.

Defending champion Fabio Quartararo, however, extended his lead atop the world championship standings despite finishing eighth.

Australian Miller finished 3.409 seconds ahead of Red Bull KTM's Brad Binder, who snatched second place from Pramac Ducati's Jorge Martin with a late overtake.

Starting seventh on the grid, Miller overtook early leader Martin in the third lap, and never looked to be in threat of relinquishing his lead from that point on.

"I can ride a motorcycle sometimes," Miller joked after the win. "I felt amazing all weekend since I rolled out in the first free practice.

"It's awesome. We've got a home Grand Prix coming up shortly and my wedding coming up in a couple of weeks, so I'm over the moon."

Saturday's qualifying was hampered by rain, but there was barely a cloud in sight on Sunday as the Japanese Grand Prix made its return after a two-year COVID-19 enforced break.

Yamaha's Quartararo extended his championship lead to 18 points from 10 with four races remaining, as his closest rival Francesco Bagnaia crashed out while attempting to overtake him on the last lap.

Aprilia's Aleix Espargaro, who is third in the overall standings, saw his chances of winning a first championship take a massive blow after he was forced to pit with a problem before the race even started and finished outside the points in 16th.

Honda's six-times MotoGP champion Marc Marquez claimed his first pole in three years on Saturday but was unable to hold on to his advantage for long and was overtaken on the first lap, eventually finishing fourth.

Yamaha RNF's Darryn Binder and Honda wildcard Tetsuta Nagashima crashed out, while Suzuki's Alex Rins was forced to retire due to a mechanical issue.