AND now it gets serious. After a flaccid February, Mayo have whipped themselves into spring shape by winning three consecutive league outings, each performance arguably better that the previous one.
Now, James Horan has revealed his league intent, too, by naming 12 of his All-Ireland starters for tonight's rematch with the Dubs. All of which means it's turning serious for Jim Gavin's 2013 trailblazers too.
All-Ireland champions are always given a certain leeway when a new season dawns; they tend to be playing training ground catch-up on the rest while, frequently, there are legacy injuries to address and resultant selection headaches.
Dublin actually enjoyed a positive league start, winning their first two matches, and they revealed plenty of their trademark 'pulverisation by pace' when ripping through Kildare three weeks ago.
But? Well, sandwiching that 10-point victory were two slices of reality that didn't taste so appetising on the palate. They lost at home to Cork and then suffered the fate that befalls most teams entering fortress Celtic Park.
Statistically, two league defeats eclipses the entire number of losses – one – shipped by Dublin throughout last year's league and Championship.
Moreover, the erratic performance in Derry reinforced the suspicion that, while Dublin's depth of talent may be envied by most rival counties, it doesn't translate into a bottomless resource.
In certain positions – the half-back line to an extent, full-back even more so – the absence of one or two key personnel leaves them vulnerable. Mark Lynch and Co capitalised on these areas of weakness to chisel out a deserved six-point win, albeit their cause was helped by a succession of spurned Dublin goal chances, all falling to players not noted as green flag specialists.
Maybe if the prodigal and still prolific Alan Brogan had been at the end of those moves, it might have been a different story. Or if brother Bernard had been on the pitch.
Enough idle hypotheticals. Fact is, Dublin are stuck on six points and neither of their remaining two regulation league rounds – Mayo tonight in Croker, Tyrone in Omagh eight days later – qualify as remotely routine.
Suddenly, the presumption that Dublin would coast into the semi-finals is open to scrutiny. Their chances would be greatly facilitated by the availability of a defensive bulwark (Rory O'Carroll), a ball-winning magnet (Paul Flynn), a mercurial genius (Diarmuid Connolly) and a merciless executioner (Bernard Brogan) as this league draws to a climax ... last night's team announcement may not address all such areas of concern, given Gavin's penchant for 11th hour adjustments.
In fairness to management, their options have been greatly constrained by the cumulative obstacles of old and new injuries, St Vincent's All-Ireland club march and Dublin's ongoing U21 campaign.
Against Derry, just six of their All-Ireland 15 took the field for the throw-in. Now, measure that against tonight's Mayo selection: 12 of their September bridesmaids are named to start.
The absent trio are Chris Barrett (back in full training after a lengthy knee injury absence), Séamus O'Shea (who has featured off the bench recently) and Alan Dillon (still sidelined by a long-term groin problem) ... in their stead, you have Brendan Harrison and the two Jasons – Gibbons and Doherty.
Tom Cunniffe impressed on his last Croke Park appearance – just 12 days ago, for Castlebar Mitchels against St Vincent's – and now he comes straight back into the Mayo team at corner-back. Skipper Andy Moran has recovered from a shoulder injury and will hope to reprise last September's goalscoring performance, with a different outcome of course.
Scoring league goals has been no problem for Mayo, who have amassed 10 in five games; this compares favourably to Dublin's surprisingly threadbare three, and just one goal in their last four.
Mayo's lust for goals should set off some alarm bells in the capital, especially considering how that Dublin full-back line has looked suspect in recent games. The counter-argument? Dublin have still only conceded five goals (one in each of their five outings), whereas Mayo have coughed up a total of 10. That's a scary figure for a team boasting three current All Star defenders – Lee Keegan, Colm Boyle and Keith Higgins, albeit the latter is once more selected at centre-forward.
In summary, tonight's outcome is mired in so many imponderables. You have Mayo's more compelling March form versus Dublin's pressing need to stall any talk of a mini-slump. You have Gavin's record against Mayo (three wins from three last year) versus Mayo's record when Dublin are All-Ireland holders (two wins from two in 2012).
One thing we can be certain of: When Dublin and Mayo lock swords, sparks fly and scores rain from everywhere. Prepare to be entertained...
ODDS: Dublin 8/13, Draw 9/1, Mayo 13/8