|Stoner has won two races in a row having failed to finish first in any previous MotoGPs this season [AFP]
Australian Casey Stoner stormed to his second successive victory for Ducati at the Japanese MotoGP as world champion-in-waiting Jorge Lorenzo finished fourth.
The fast-starting Stoner continued his hot form at Motegi's Twin Ring circuit but the real drama unfolded behind him as Lorenzo locked horns with Yamaha teammate Valentino Rossi.
The Ducati rider passed Honda's pole-sitter Andrea Dovizioso almost as soon as they had exited turn one and never looked back, finishing almost four seconds clear of the Italian.
"It was pretty much a lucky dip for the race as to how well the bike was going to work," Stoner said.
"To win here was completely unexpected going into the race.
"We were the underdogs coming to this track but it worked out. It was awesome."
Behind the front two a furious battle raged between Yamaha's Lorenzo and Rossi, the pair clashing repeatedly and their bikes scraping against each other with two laps left in a hair-raising finale.
Rossi held off Lorenzo to keep his team mate off the podium for the second race in a row, although the Spaniard stretched his lead in the title race to 69 points.
Lorenzo is virtually assured his first premier-class world title after countryman Dani Pedrosa fractured his collarbone in Friday's practice.
Lorenzo has 297 points to Pedrosa's 228 and can clinch the championship by scoring just seven points next weekend in Malaysia.
Pedrosa is recovering in a Barcelona hospital from surgery after to fix a titanium plate to his damaged shoulder and Honda have yet to say when he will return.
Stoner, who also won at Aragon last month, is third in the standings on 180 points with four races remaining.
Spain's former MotoGP rider Toni Elias won the Moto2 race, 0.315 seconds ahead of compatriot Julian Simon.
The win allowed Elias to extend his lead in the overall standings to 81 points over Simon.
Spain also dominated the 125cc race with Marc Marquez winning with a 2.612-second gap over Nicolas Terol.
Terol leads the overall standings with 228 points, six points ahead of Marquez.
A special ceremony was held on the podium for Moto2 rider Shoya Tomizawa, who was killed when he fell and was hit by two trailing bikes in San Marino on September 5.
Tomizawa's parents were presented with a plaque displaying his number 48, which has been retired from the championship in his honour.