It was a Showdown of the highest order and the type of brutal test Adelaide needed heading into the finals.
Form lines went out the window as much-maligned Port Adelaide produced its best performance of the season to push the Crows to the brink.
But five goals to the mercurial Eddie Betts in his 250th game helped the Crows secure a 15-point win in front of a sold-out crowd of 49,451 at Adelaide Oval.
The 15.19 (109) to 14.10 (94) victory moves the Crows to second on the ladder and in the box seat to grab a home qualifying final.
Adelaide midfielder Matt Crouch had a brilliant game with 33 possessions while Betts, Mitch McGovern, Tom Lynch, Josh Jenkins and Taylor Walker kicked 14 goals between them.
Ollie Wines led the Power with 28 possessions while Robbie Gray and Travis Boak had 27 and 26 touches each.
Adelaide coach Don Pyke was impressed with how the Crows withstood the Power's third-quarter fightback.
“Our ability to keep going - there were times in that game where … Port Adelaide got a bit of a run on," Pyke said.
“I thought our guys showed a bit of maturity just to stick true.”
Power coach Ken Hinkley said he was proud of how his side challenged a premiership-contending team given Port’s recent poor form.
"I do walk away losing so that disappoints me and the playing group, there's no doubt about that,'' Hinkley said.
"But the way we went about it tonight, I thought we stuck to some stuff that was pretty strong all night and we gave most of what we had, I reckon.
"That's all you ever ask of them."
The Power went into Showdown XLI as the biggest underdogs in the clash's 20-year history, but they made the perfect start when Gray booted the game's opening goal with a left-foot snap inside the first two minutes.
The Power attacked contests with vigour, looked dangerous in attack and weren't committing the skill errors that have plagued their season.
The Crows responded, as we knew they would.
Betts kicked three of his side's four goals in the opening quarter, but two to Aaron Young helped the Power take an unexpected one-point lead into the first break.
Wines was everywhere early, racking up five tackles in the first 15 minutes, while Crows champion Rory Sloane quickly had half a dozen touches.
Concern turned to the health of Adelaide wingman Brodie Smith who left the ground on a stretcher in the second quarter with concussion after copping an accidental boot to the head.
Smith suffered two concussions last year and he must be in doubt for Friday night's blockbuster with West Coast.
The Crows couldn't capitalise on their dominance, kicking six points in a row before Lynch slotted one home from 45m out.
Betts then kicked his fourth – and set a career-high of 64 goals in a season – as Adelaide threatened to blow the game open.
Stats can often be deceptive, but these ones aren't.
In the second quarter, the Crows had a staggering 22 Inside 50ms to six and 12 scoring shots to three.
Late goals to Jake Neade and Young gave the Power a sniff and pulled the margin back to 13 points at the main change.
The biggest question was how long Port could maintain this intensity with nothing but state pride on the line?
With the Crows threatening to pull away, Jared Polec burst through the middle and launched into a shot from the edge of the centre square before the ball took a favourable bounce.
Adelaide continued to hit back, but the Power stayed close.
Gray produced a Goal of the Year contender, Neade manufactured something out of nothing and captain Travis Boak snapped high and true to bring Port Adelaide to within a point.
Coach Ken Hinkley moved the team's three-quarter time huddle to in front of their most vocal supporters to get them up for their last home game of the year.
The Power fought hard in the final term, but Betts' fifth goal in trademark fashion from the boundary sealed the result.
What a game from the milestone man tonight ! #250ofthebetts #weflyasone pic.twitter.com/DnmAP0Ubb1
— Adelaide Crows (@Adelaide_FC) August 20, 2016
MEDICAL ROOM
Port Adelaide: Nil
Adelaide: Brodie Smith was stretchered off in the second quarter with a concussion after copping an accidental boot to the back of his head. Smith was also concussed last season in a match against St Kilda.
NEXT UP
The Crows have the perfect warm up for the finals with a huge clash against the in-form West Coast at Adelaide Oval on Friday night. Meanwhile, the Power will be aiming to finish its season on a high when it takes on Gold Coast at Metricon Stadium next Saturday.
PORT ADELAIDE 4.3 6.4 12.7 14.10 (94)
ADELAIDE 4.2 7.11 11.14 15.19 (109)
GOALS
Port Adelaide: Young 3, R.Gray 2, Neade 2, Palmer, Westhoff, Polec, Toumpas, Boak, Amon, Broadbent
Adelaide: Betts 5, McGovern 3, Lynch 2, Jenkins 2, Walker 2, Brown
BEST
Port Adelaide: Wines, R.Gray, Boak, Impey, Polec, Ebert
Adelaide: M. Crouch, Lyons, Sloane, Thompson, Atkins, Betts
INJURIES
Port Adelaide: Nil
Adelaide: Smith (concussion)
Reports: Nil
Umpires: Farmer, Kamolins, Harris
Official crowd: 49,541 at Adelaide Oval