And now we know. The big, unanswered question about this Dublin team - until yesterday - was how they would react if they were ever led into a very dark, foreboding place by heavyweight opponents who scented Sky Blue blood.
It happened here, at various stages between the hours of four o'clock and shortly after 5pm.
Their response, jittery for a few fleeting minutes before half-time, was ultimately emphatic and carried the hallmark of true champions.
The odds on Jim Gavin's Dublin completing their two-in-a-row odyssey have now been slashed into 2/7, with just Mayo - those perennial pretenders - now blocking their path on September 18.
It's hard to disagree with our turf accountant experts, partly because there is so much talent in this Dublin squad, and such collective resilience, but also because they have now received - in the words of Éamonn Fitzmaurice - a "great gut-check".
They have been tested, every bit as forensically and ferociously as they were when these two counties slugged it out in that 2013 All-Ireland semi-final for the ages.
Yesterday's semi-final warrants favourable comparison, even if there were four less goals on offer. Instead we were compensated with a roller-coaster ride for all concerned - players, management, partisan fans and neutrals alike - as the scoreboard and momentum, not to mention emotions, oscillated wildly.
Did we have a deserving winner at the finish? Yes, just about, for a variety of reasons - the most telling one being that Dublin were the dominant force for a far greater portion of the contest.
But then why, or how, were their back-to-back ambitions left teetering on the edge of oblivion?
You can answer that by recounting what happened during 13 crazy minutes, from the 25th minute until half-time sounded just after an injury-time free converted by Colm Cooper.
When Ciarán Kilkenny soared to pilfer a Brian Kelly kickout and tee up Diarmuid Connolly for his second point, the rampant holders led by 0-9 to 0-4 and Kerry (just like Donegal at a similar semi-final juncture two years ago) looked on the cusp of obliteration.
But they wouldn't score again before the interval. And Kerry would hit them, incredibly, for an unanswered 2-4.
A five-point game for Dublin had become a five-point game for Kerry. And it had stemmed, largely, from something of a mid-game meltdown from Stephen Cluxton.
The excellent Paul Geaney launched the comeback with his third point in a haul that would eventually reach 1-4 from play. Colm Cooper trimmed the deficit further with a 30th minute free.
And then, as Cluxton prepared to restart, we had the intriguing sight of Kerry going full-mettle full-press - even leaving just two defenders back on four forwards.
Instead of kicking long, where Dublin were sure to have a numerical advantage, the veteran 'keeper swung his kickout short towards the right touchline. His intended target was John Small, but Geaney pounced before it got there and released Donnchadh Walsh, whose first-time flick pass found Darran O'Sullivan for a point-blank finish.
In that instant, bizarrely given that first half-hour, Kerry were level. Cluxton lost two of his next three kickouts, including one over the sideline. He wasn't the only Dublin temporarily reeling but, after Cooper kicked Kerry ahead, he suffered nightmare on the double in the first minute of stoppage time.
Again, it came from an unlikely source: a point attempt from Anthony Maher that dropped just under the crossbar. But the inrushing Geaney - not Cluxton - was the player who attacked it with intent, and he got just enough purchase to divert the ball goalwards.
Cluxton desparately clawed it back; but the umpire was in the perfect position to judge and he deemed it had crossed the line. However marginal, it looked the correct call.
What was beyond argument is that Dublin's title was now hanging by a thread. They've had a few ropey halves this summer, but nothing to compare with a five-point deficit against a serious rival.
Moreover, a rival already consumed by revenge for those three previous summer losses and one that now had its dander up.
Half-time, though, was the ultimate blessing for Jim Gavin. Dublin took their smelling salts, refocussed and set about dominating Kerry all over again.
They would land six of the next seven points to draw level before we'd even hit the 50-minute mark.
There was still time for a three-point Kerry retort, launched by Barry John Keane who marked his arrival with a sublime touchline score. Even beyond the hour, they were still three up after a Paul Murphy point.
But then - just as happened in 2011 and 2013, and even at the end of this year's league final - Dublin cut loose in the home straight to sicken their long-time nemesis turned victim.
Philly McMahon's wanderlust tendencies took him deep into enemy terrain for a 62nd minute point, the first of four that would finish with Kevin McManamon (who else?) firing Dublin ahead on 70 minutes.
Stephen O'Brien's fisted equaliser was then countered by Eoghan O'Gara. With Kerry chasing another leveller, Peter Crowley's run into Bryan Sheehan range was unceremoniously ended by a crunching McManamon shoulder, one which looked far less legitimate on replay, and the resultant move eventually ended with an exquisite insurance point from Connolly.
Game, set and classic.