Macedo swept in late as others around him suffered all manner of misfortune in a feature played out on a wildly treacherous track.
In form Tasmanian Jock Goodyer led the issues for the top handful of contenders, suffering engine problems whilst leading.
That gave top spot to Marcus Dumesny who bicycled through Turn 2 allowing Macedo through.
Earlier James McFadden retired from running third, and Jamie Veal spun racing for fourth.
Only half of the 20-car field finished the 35-lap final, played out on a bumpy surface following scorching hot temperatures.
Macedo took the checkered flag and $10,000 prize purse following on from his Avalon Speed Week success on December 30.
He beat home a dejected Marcus Dumesny who had to settle for second, with Cam Waters continuing his promising run of form, rounding out the podium.
“To get a result like this with such a quality field is huge for me and my team,” Waters said.
“It’s still such a buzz racing against the likes of McFadden and Macedo who are guys I admire – I’m loving this sport.”
For Macedo it was a late call mid-week just to make the trip to Victoria to run at Avalon in the new event.
He’s now glad he did.
“This is just about the best run of form we’ve had in Australia, with a couple of wins here at Avalon and our Toowoomba win last weekend,” Macedo said.
“It’s the perfect time to be performing with the Classic next week, so hopefully it continues.”
The biggest week in Australian speedway kicks off on Wednesday night back at Avalon for the President’s Cup, ahead of next weekend’s 51st edition of the Grand Annual Sprintcar Classic.