Slow-burning Kerry have yet to peak - and that's ominous for Mayo
So which is the real Mayo? The one that lost to Galway and had to battle through the qualifiers, stopping off for two periods of extra-time before drawing with Roscommon in the quarter-final, or the one which won the replay with one of the most impressive performances of the summer?
If it's the former, they won't even test Kerry but if it's the latter, they have a good chance of reaching the final for the fourth time in six seasons.
Qualifying for the decider three times in five seasons was quite a feat, but as neighbours Galway can testify, that level of consistency carries no guarantee that the ultimate destination will be reached.
They lost the 1971-'73-'74 finals but then headed into a deep recession, winning only one of the next seven Connacht titles and not reaching another All-Ireland final until 1983, where they were also beaten.
Mayo realise that the opportunity lane is narrowing for an ageing team. And while they don't appear to be coming under any great pressure from the younger generation - scarcely a healthy sign for the future - the changing of the guard cannot be too far away.
Next year, Andy Moran, David Clarke and Alan Dillon will all be 34 years old, Keith Higgins (33), Colm Boyle (32), Chris Barrett, Seamus O'Shea and Ger Cafferkey (31), Tom Parsons (30), Kevin McLoughlin and Donal Vaughan (29).
It's an age profile that makes tomorrow and, hopefully from a Mayo viewpoint, September 17 so important.
The Kerry squad isn't exactly in the early stages of its cycle either, with Kieran Donaghy (34), Donnchadh Walsh (33), Darran O'Sullivan (31), Anthony Maher and Killian Young (30), Shane Enright and David Moran (29) taking the average age to the higher end of modern-day trends. As with Mayo, the Kerry squad is likely to undergo an extensive overhaul if Sam Maguire doesn't winter in the south-west.
Mayo's demolition of Roscommon has restored confidence levels in the county, with supporters convinced that the camp has timed its run to perfection, peaking for tests that will be completely different to anything they encountered so far this season.
They may be right but it also has to be acknowledged that Roscommon bombed collectively and individually. Their defence virtually waved Mayo through and with Roscommon unable to win much possession around midfield, sporadic attacks were easily repelled.
Kerry will present a very different proposition. Granted, their defensive alignment was unconvincing in the championship so far, allowing Cork and Galway to create several goal opportunities, none of which were taken.
Still, Kerry had earlier beaten Dublin - complete with the highest-rated attacked in the game - in the Allianz League final. It suggests that perhaps they weren't fully tuned in for the clashes with Cork and Galway, games they always felt they would win.
Eamonn Fitzmaurice's comment that he was 'disappointed' after beating Galway supports that theory. It says a lot for Kerry's expectations - and indeed for their perception of Galway as a limited outfit - that an eight-point win wasn't enough to satisfy the manager.
Galway had earlier beaten Mayo, a result which probably would have been different if Higgins was not dismissed in the first half.
Mayo have been asked a lot of questions this summer and, with the exception of the Galway poser, they have answered them all, albeit with a struggle in some cases.
Still, they are now in line for a much more forensic interrogation and this time they may not have all the correct responses.
Kerry by 3-4 points.