Marco Simoncelli emerged on top of a race long battle with 250cc World Championship rival Alvaro Bautista to win the Australian Grand Prix by just 0.223secs.
The Metis Gilera rider dropped from pole to fourth at turn one, but was up to second place behind Bautista by lap two of 25 and took the lead later on the same lap.
The pair fought for the remainder of the race, the repeated passes allowing the KTM trio of Hiroshi Aoyama, Mika Kallio and Julian Simon to join the victory fight for the first half of the race.
But the superior pace of Simoncelli and Bautista soon began to tell, and they were over ten seconds clear of third by the closing stages.
Simoncelli led at the start of the last lap, but a defensive line into the MG hairpin allowed Bautista to get a better exit. Their paths crossed at the apex of the following turn, forcing Bautista to lift. Simoncelli also bobbled, but Bautista couldn't capitalise and Simoncelli held on for his fifth victory of the season.
Simoncelli is now 37 points clear of Bautista with just 50 points remaining and therefore has an excellent chance of wrapping up his first world title next time out at Sepang.
Meanwhile, Aoyama retired with a technical problem during the second half of the race - prompting the usually controlled Japanese to punch down a temporary wall inside the KTM pits with frustration - leaving colleagues Kallio and Simon to fight for the final podium position.
Simon looked to have third in the bag exiting the final corner, but was slipstreamed by Kallio on the run to the line. Double 2008 race winner Alex Debon held off Roberto Locatelli and Yuki Takahashi for fifth.
Race results - Phillip Island:
1. Simoncelli (Gilera)
2. Bautista (Aprilia) +0.223secs
3. Kallio (KTM) +14.450secs
4. Simon (KTM) +14.478secs
5. Debon (Aprilia) +26.226secs
6. Locatelli (Gilera) +26.392secs
7. Takahashi (Honda) +26.434secs
8. Espargaro (Aprilia) +40.546secs
9. Wilairot (Honda) +1min 0.219secs
10. Lai (Gilera) +1min 20.825secs