Ryggs Johnston's putter proved a lethal weapon as the American rookie won the men's tourney of the 1.7 million Australian dollar ($1.11 million) Australian Open by three strokes for the biggest win of his career at a wet and wild Kingston Heath on Sunday.

South Korea's former world No. 1 Shin Jiyai won the women's trophy in the dual gender event by two strokes, overcoming late nerves and a charge from defending champion Ashleigh Buhai to claim the title 11 years after her first.

While Shin made sure of her win by storming to a seven-stroke lead midway through, Johnston wielded magic on the back nine greens to see off an unlikely challenge from unheralded Western Australian Curtis Luck.