Western Australia posted its first win of the NAB AFL Under-18 Championships at Joondalup Arena on Saturday, after losing to Queensland by four points last weekend.
They won 14.17 (101) to 5.5 (35).
Simpson spent almost two months on the sidelines following a heavy collision playing with East Fremantle in the WAFL in April.
But he was fit and firing against the Rams, displaying some key overlap run and efficient ball use for his home state.
After a stint at Adelaide's prestigious Rostrevor College, the 18-year-old recently moved back to Western Australia to be closer to his family, who hail from Geraldton.
The South Australian under-18 program managers were bitterly disappointed to lose Simpson, who gave a glimpse of his talent for the state in last year's championships.
Western Australia made the Rams pay for a number of misguided turnovers, slicing them open with a strong work ethic and sharing the ball effectively.
Sean Lynch (24 disposals), Dayle Garlett (20) and Jack Martin (20) were all instrumental in the Sandgropers' win.
For NSW/ACT, Tom Hargreave (26) and Zac Williams (20) did their utmost to lift their side.
But the Rams' poor disposal led to frequent turnovers, which would have frustrated coach Jason Saddington.
WESTERN AUSTRALIA 3.3 7.7 12.11 14.17 (101)
NSW/ACT 1.2 3.3 4.4 5.5 (35)
GOALS
Western Australia: Shaw 3, Simpson 3, Paparone 2, Hogan 2, McKenzie, Chalmers, Sheed, Martin
NSW/ACT: Hampton, Hargreave, Taylor, Vearing, West
BEST
Western Australia: Lynch, Garlett, Simpson, Hogan, Lowrie, Martin
NSW/ACT: Williams, Robinson, Hargreave, Harper, McGillivray
