The two-time event winner managed five birdies in a six-hole stretch to be four under through 11 holes at Brisbane's Royal Queensland Golf Club on Thursday.
Starting on the 10th, Scott dropped a shot on the 14th but, as squalling rain set in at the riverside venue, found his groove.
He nailed his approach to the 18th for a tap-in birdie then added another on the par-four first and second to be one shot clear of Elvis Smylie and Min Woo Lee.
Seven others, including Poland's 2022 Australian Open champion Adrian Meronk, were sitting a shot back.
Scott's playing partner Cameron Davis found the sand on the 18th and missed his par putt to fall to one under.
Cameron Smith, playing alongside Lee in front of a sizeable gallery given the weather and early start, found the same trap but was deft with his sand wedge to save par.
The defending champion and three-time winner mixed one birdie with a bogey to be even par at the turn.
Scott won this event when it was last held at Gold Coast's Royal Pines in 2019 and followed it quickly with a 14th PGA Tour triumph in early 2020.
But he hasn't lifted a trophy since, declaring on Wednesday that he wasn't home just to make up the numbers.
"It's hard to fake that confidence of closing out a tournament, beating the entire field," he said.
The 2013 Masters champion launched that historic campaign with a maiden PGA victory on the Gold Coast.
"If I were to win this week or next (at the Australian Open in Sydney) it could be a springboard," he said.
"It's happened before, not just with me."
