The Lions were leading by 40 points with about 13 minutes remaining in the final term on Friday night when a surge plunged the Brisbane stadium into darkness, except for a lone bulb in a light tower that was on fire.
Enough light returned before the 60-minute cut off that would have handed Brisbane victory.
The hosts eventually prevailed 14.9 (93) to 13.4 (82), with a sigh of relief after flatly conceding five unanswered goals once play resumed.
In bizarre scenes, the players had stood on the ground for several minutes before heading inside as power slowly returned to the ground.
Players reappeared about 30 minutes after the outage to warm up - and suddenly they were back underway.
It was a confusing sequence of events but not the first time it's happened at the Gabba, with a Big Bash League fixture in 2019 ended early by a power outage.
The MCG scoreboard caught fire in 1999 while in 1996 disgruntled fans lit fires on the surface and in the stands of Waverley Park when a blackout forced St Kilda and Essendon's clash to be completed a week later.
There were contrasting scenes at the Gabba, though, as 30,047 cheery fans broke into song waiting for a resumption.
Earlier the Lions, still smarting after a first-round hiding from Port Adelaide, shot out of the gates with six first-quarter goals while Demons star Max Gawn left the game with a knee injury.
The ruckman cutting a devastated figure and will wait on scans hopeful of no long-term injury.
Steven May was a pre-game scratching and the Lions went in for the kill, Melbourne's second-quarter resistance blown apart with two early third-quarter goals that looked to have sealed a win for Chris Fagan's side.
Brisbane upset the Demons in last year's semi-final and Fagan was keen to show it was no "fluke", especially after their slack Adelaide Oval effort last Saturday.
Playing at half-forward, Dayne Zorko (22 touches, two goals, eight inside 50s, four tackles) showed how important he remains to Brisbane after missing round one, while Cam Rayner was electric in defence and Will Ashcroft (31 touches) a midfield jewel in his second AFL game.
Brisbane blew the Demons apart in the clearances, winning 60-32.
Early pressure from Jarrod Berry - who left the field late with an apparent shoulder injury - helped restrict Clayton Oliver to one first-half clearance, but he still finished with 37 disposals.
Ben Brown (three goals) and Bailey Fritsch took their chances to get the Demons back within 20 points in the second quarter, but quick Charlie Cameron and Joe Daniher goals to begin the second half snuffed them out.
Zorko's running goal - his second - made it a 39-point game and, after two Demons goals, Lincoln McCarthy chimed in to close the quarter.
Teams went goal-for-goal early but the Lions exploded late in the first quarter, notching 14-straight inside 50s and producing four goals.
With the forlorn Gawn icing his knee in the dressing room, Zorko, Ashcroft, Oscar McInerney and Daniher all hit the scoreboard to create an early 25-point lead.
