Comment - Bench press holds the key for Dublin in final face-off
For many it was the decision that opened their eyes to the wealth of talent at the disposal of Dublin manager Jim Gavin.
Victory over Tyrone was already assured but Gavin didn't turn to his bench to introduce Diarmuid Connolly until the game went into injury time. It seemed odd, given that much to Gavin's chagrin Connolly had been suspended for 12 weeks. But his manager decided he could afford to make him wait another 70 minutes before finally letting one of his most celebrated footballers off the leash.
On the face of it it was an essentially meaningless cameo. But the introduction of the St Vincent's man in place of one of the game's emerging stars Con O'Callaghan was Gavin's final change, meaning that two former Footballers of the Year, Bernard Brogan and Michael Darragh Macauley, would not see action.
Having the luxury of holding such thoroughbreds in reserve suggests Dublin's golden era shows now sign of stopping.
Still Mayo will be tipped to - at the very least - bring Dublin to the brink.
Such expectation is founded in the sound logic of recent history. The likes of David Clarke, Stephen Cluxton and others have been at the coalface of this rivalry for more than a decade now. The famous 2006 All-Ireland semi-final clash saw Mayo win by a point and it has set a pattern. In the six championship clashes since, two have finished in draws and two have ended in one-point wins.
In fact, only one - the 2015 All-Ireland semi-final replay - has been decided by more than a single score.
So the teams have been shown to be well matched and no one will be surprised if they are neck and neck coming down the home straight, meaning that what comes off the bench could have a big say on where Sam Maguire will spend the winter.
A quick glance suggests Dublin are better equipped in that department. In all Gavin has used 29 players in this year's championship with 11 of those starting every game but perhaps it is the names we are seeing less of that is most striking.
Macauley has only been seen once as he battles with a knee injury. Four-time All-Star Paul Flynn is being eased back into action and didn't appear in the Leinster series at all. Brogan has yet to start a game. Connolly hasn't touched the ball in championship action since the Carlow game. Kevin McManamon hasn't started a game since he took to the field against Carlow. Last year's All-Ireland final replay game-breaker Cormac Costello hasn't seen a minute of action though is fully fit, according to his manager.
In that period Dublin have evolved before our eyes. Once-in-a-generation players like Flynn and Brogan suddenly have to make do with roles as deputies. O'Callaghan stepped up to the plate when Dean Rock was shown a black card against Kildare and held his nerve when handed the free-taking duties ahead of Brogan while physically Paul Mannion is a more imposing player.
They have been getting a reaction from those left out too. The bench contributed 1-4 against Tyrone. The replacements could only manage two points against Monaghan but it contributed seven points in the win over Kildare and 2-5 in the hammering of Westmeath in Leinster.
Sean Cavanagh was impressed enough to state that Dublin were effectively able to leave their 'best players' on the bench and still see off his Tyrone side with something to spare.
"I think Mayo are going to have to bring some sort of an X-factor to beat Dublin, I think they're going to have to... whether they go man for man, or get them embroiled in a row. They're going to have to do something," the recently-retired Tyrone player said.
"They're going to have to push Dublin to a different zone because the way they were against us, they were in cruise mode. And their best players were sitting on the bench. It's amazing."
For Cavanagh, Dublin's less-known players have assumed the leadership roles in the side.
"You're matching up against other counties and you know who you have to stop. I didn't believe that some of their so-called lesser known players were as good as they were until you saw them in the flesh and seen the pace that they have and the skill that they have and the way they work as a unit.
"I have to hold my hands up, I was incredibly (impressed) by their whole set-up, their whole machine. Jim Gavin has done an incredible job and I believe they will beat Mayo fairly comfortably as well."
Mayo have less in the way of decorated stars to come in off the bench but that hasn't stopped Stephen Rochford from going deep into his panel across their nine-game odyssey this summer. In all he has used 27 players with five of those starting every game and another five featuring in each game in some form.
It hasn't been plain sailing. He has shipped some criticism this year for taking off the likes of Colm Boyle and Andy Moran but insisted their changes were well thought out.
"We would feel that we have a bench to come on to make an impact," said Rochford.
"A lot of guys in those games - take the Cork game, the first four guys (in off the bench), three of them had started the All-Ireland final and the All-Ireland final replay last year.
"So, you're not on about giving young fellas a run out. You're tactically trying to push the game on. At no stage were we bothered or getting distracted by the commentary outside of the group.
"And at no stage was there anything within the group that was sort of wondering why a fella was in, or why a fella was coming in off the bench. Nobody was being distracted by it."
The numbers show that Mayo aren't pulling the same scoring returns off their bench but they have made a significant contribution nonetheless. Paddy Durcan would start for most teams in the country but he was held in reserve for the first game with Kerry. That decision was vindicated when he came on to kick the equaliser.
Mayo would pull three points off the bench in the replay with two coming from Conor Loftus, who also rescued them with a late goal against Derry.
Rochford hasn't been afraid to change either. Donal Vaughan started the year on the bench but has started the last three games while Andy Moran finished both games against Kerry.
The pieces on the board look well matched. Perhaps it will come down to who makes the best use of them.