Hiroshi Aoyama brought himself to the brink of the 250cc world championship by defeating title rival Marco Simoncelli in an epic Sepang race.
With Simoncelli pushed down to third behind Hector Barbera in a frantic last lap, Aoyama's championship lead is back up to 17 points, with just 25 available at the Valencia finale.
The title fight is now a two-way contest, with second not sufficient to keep Barbera in contention, and fellow long-shot Alvaro Bautista crashing for the third straight race when running fourth early on.
Aoyama lost the lead to second place qualifier Jules Cluzel off the line, while Simoncelli quickly made progress from his disappointing eighth on the grid.
When Aoyama slid wide in a failed move on Cluzel on lap two, he slipped to fourth and found Simoncelli right on his tail - and then ahead of him as the Italian sliced inside his title rival at Turn 2.
The duo then picked through to the front of the field together, with Aoyama all over the back of Simoncelli. The Scot Honda went down the inside into the last corner on lap six, but Simoncelli had a better exit and eased Aoyama out over the curbs, letting Cluzel get back between them.
Aoyama was soon back on Simoncelli's tail and repeated his hairpin pass at half-distance. Simoncelli drafted back through on the straight, Aoyama outbraked him again into Turn 1, and then Simoncelli nipped back down the inside at Turn 2.
Two laps later Aoyama surprised Simoncelli into Turn 9 and reclaimed the lead. Simoncelli again fought back on the pits straight and again the pair went through Turns 1 and 2 side by side, inches apart. But this time Aoyama got back ahead as they accelerated through the Turn 3 kink, resisted Simoncelli's retaliation at Turn 5, and then finally made a break.
A string of new lap records took Aoyama into a comfortable lead, while Simoncelli had his hands full fending off Barbera, who slipped ahead at the final corner at one point only to run very wide.
Barbera stepped up his attack on the last lap, getting alongside on the dash to the line and taking the flag in a dead-heat with Simoncelli. They could not be split on video evidence so Barbera was awarded the place because his fastest lap was quicker than the Italian's.
Cluzel crashed out at half-distance. As well as the Frenchman and Bautista, other riders to fall while in the top ten included Mike di Meglio and Mattia Pasini.
Thomas Luthi recovered from a first lap wobble to fight through to fourth, with Hector Faubel beating Ratthapark Wilairot and Alex Debon to fifth.