Stoner used his fourth pole position in a row to take an early lead, while second on the grid Rossi dropped to third behind
John Hopkins. Just behind them, Kawasaki's
Randy de Puniet collided with
Dani Pedrosa at turn two - bringing them both down and forcing Pedrosa's Repsol Honda team-mate
Nicky Hayden, who had made a poor start from the front row, into the gravel.
Chris Vermeulen, fastest in morning warm-up, wasted no time in passing Rossi for third early on in the first lap - but greater drama was to follow when the Italian suffered a shock engine failure on lap five, silencing the 57,321 fans. Rossi had been using the new M1 engine, featuring pneumatic valves, for the first time in a race.
Rossi, whose home town of Tavullia is just ten miles from Misano, began the event 60 points behind Stoner and The Doctor's second DNF of the season - after an accident at the Sachsenring - meant not only the end of his home victory streak, having won the last six Italian Grands Prix at Mugello, but also the end of his realistic 2007 world championship hopes.
With just five races and 125 points still up for grabs, Stoner is now 85 points clear of Rossi and is it theoretically possible for the 21-year-old to wrap up his and Ducati's first MotoGP crown next time out in Portugal, although the following Japanese Grand prix is most likely.
As last time out at Brno, and unfortunately for
MotoGP's worldwide TV viewers, Stoner led from start to finish - and again a Suzuki rider provided his nearest opposition, this time in the form of fellow Australian Chris Vermeulen, who overtook team-mate Hopkins shortly after Rossi's withdraw.
The Le Mans winner then closed to within one second of Stoner, but by the halfway stage Casey had pulled 1.8secs ahead and Stoner eventually won his eighth race of the season by a margin of 4.851secs… then ran out of fuel on the slowdown lap!
