Just as he was expected to ride into history, why is Stoner instead riding into the sunset?
If his sport was simply about racing bikes at high speed, two-time MotoGP world champion Stoner would not be quitting at the peak of his powers.
But it is the circuit life and its off-track demands, and where he sees the sport heading, that have sapped love from marrow.
Stoner, who has battled illness and injury throughout his career, knows also the extraordinary stress MotoGP riding puts on bodies.
Bodies which absorb phenomenal shudder and force for 20 races and countless laps a year, not to mention the regular high-speed crashes - even for great riders like Stoner.
So many past champions walk with a limp or shake hands with bent, wizened fingers.
From a bike, there is nothing to catch you when you fall.
Stoner has chased the dream since he was 14 - moving with his family to England to work his way through the road racing classes.
These days, he has his own family - wife Adriana and baby daughter Alli - and a wish to spend quality time with them.
Stoner goes into Phillip Island just weeks after ankle surgery to repair a serious injury following a fall.
It wrote off his chances of a third world crown to add to his 2007 and 2011 titles.
But he has recovered well enough - though he admits he is still in pain - to farewell Phillip Island.
"It's been built up to be a very big weekend," Stoner said. "The only thing I can do is my best."
Whatever the result tomorrow, Stoner will leave the sport recognised as one of its greats. He is fourth on the all-time world 500cc/MotoGP winners' list.
Only Italian superstars Valentino Rossi and Giacomo Agostini and Australian Mick Doohan have won more races than his 37.
At the track he has dominated since 2007, Stoner's achievements in world motorcycling will forever be recognised.
A move from two wheels to four looms as his next career move.
The late Gregg Hansford and Gardner both made the transition from the world motorcycle championship to driving touring cars.
It will come as no surprise if he excels.
Stoner has always been swift.
Sadly, so too was his top-flight motorcycling career.
-AAP