Bernhard Langer took a triple bogey at the last in Sydney yesterday to squander the chance of winning his first tournament since November 1997.
The German's remarkable lapse, which included a penalty for a marker infraction on the final hole, allowed New Zealander Michael Long to snatch the title.
Long shot a closing one-under-par 72 in the strong southerly wind, which troubled all the players, to win on 283, nine under.
He finished one shot clear of fellow countryman Michael Campbell who shot a 74. Langer was a shot further back after shooting 80.
Langer (41), needed only to par the 225-yard par-three last hole to beat Long by a shot. Langer thought he had hit his three-iron tee shot perfectly, but the ball drifted right and plugged in a bunker, 30 yards from the pin.
He then blasted the ball through the green and, when his chip finished well short, needed to sink a putt from nine feet to force a playoff with Long.
But Langer picked up his marker before replacing his ball and, after calling rules official Trevor Herden, confirmed he had incurred a one-shot penalty and could no longer win.
"I don't know, I just picked it (the marker) up," a remarkably composed Langer said. "It's never happened before and it happened today. Don't ask me why I did it. I didn't do it on purpose, it just happened."