Eamonn Sweeney: Today will solve the riddle of Tyrone
So what are Tyrone going to be like today? I don't know. Neither do you. Jim Gavin probably doesn't know either while even Mickey Harte can't be absolutely certain how his team are going to cope with the Dublin challenge.
It's possible that by 5.0pm today we will have witnessed the arrival of a new force in the game, one powerful enough to knock the hat-trick seekers from their perch. It's also possible that by 4.0pm Dublin will already have put the game to bed, their power and pace proving too much for a team which hasn't faced a serious challenge in this year's championship.
Those are the extreme possibilities. It's more likely that what happens will lie somewhere in between on the football spectrum. But who can be sure? Tyrone enter this game shrouded by an aura of mystery.
That shouldn't really be the case. They've won two Ulster titles in a row and this is their second semi-final in three years. We've seen plenty of Tyrone. Yet the impression persists that we do not know them in the same way we do the other elite teams. We don't even know if they are an elite team or merely one trapped in a limbo between the top three and everyone else.
Ask an average GAA fan to name a few Tyrone players and chances are the top three will be Seán Cavanagh, best known for what he achieved a decade ago, Cathal McCarron, best known for what he's overcome off the pitch, and Colm Cavanagh, best known for being Seán's brother.
The All-Stars Peter Harte and Mattie Donnelly will figure too but the rest of the team, which includes some really excellent footballers, toils in relative anonymity, though there may be memories of Niall Morgan kicking long frees wide and Tiernan McCann diving.
Most of Tyrone's players, like their team, await a game which defines them and finally fixes their shadowy outline firmly in the public eye. It arrives today.
The reason we remain largely in the dark about Tyrone is that the woeful lack of strength in depth in the football championship means top teams are increasingly unlikely to encounter serious competition until well into August.
The Ulster champions had an average of over nine points to spare on their way to this year's provincial title and in reality the margins between them and the opposition were even greater as Tyrone eased down considerably in all those matches. Even the 3-17 to 0-8 scoreline against Armagh in the All-Ireland quarter-final hardly reflected the scale of their dominance.
Last year's provincial campaign was slightly more rigorous with a careless draw against a Cavan side beaten by 17 points in the replay and a narrow Ulster final victory over Donegal. Yet there was something thoroughly unsatisfying about Tyrone's subsequent All-Ireland quarter-final exit against Mayo in an error-strewn game.
A combination of Seán Cavanagh's sending-off on the hour, a couple of magnificent Lee Keegan points and some awful Tyrone shooting conspired to see Mayo home by a point.
Mayo had been shaky in the qualifiers up to that and looked to be in decline. Yet their subsequent form makes that narrow defeat look far from disgraceful. All the same there was something oddly inconclusive about the game. It was another argument for a verdict of 'not proven' against Tyrone.
This year has been an absolute cakewalk for them. The stats are hugely impressive, a whopping 23 points-a-game scoring average, just one goal conceded and a truly remarkable spread of scorers with an average of 11 players hitting the target in each game.
They have been a juggernaut. Yet the opposition has been weak, even by the standards of the 2017 championship.
Armagh and Derry will both play Division 3 football next year, Down would have been there too but for an injury-time equaliser in their final league match and Donegal's collapse against Galway indicated a team in considerable disarray.
Tyrone have had by far the easiest path to the semi-final. Kildare and perhaps even Carlow gave the Dubs a bigger test than any their opponents today have faced.
It is a far cry from Tyrone's last All-Ireland final-winning year in 2008 when they actually lost their first round tie against Down and embarked on a convoluted progress through the qualifiers, scraping past Mayo, being thoroughly tested by a Westmeath team who'd almost beaten Dublin in the Leinster semi-final, then shocking the Dubs in the quarters before getting a tough test from Wexford, the type of overachieving underdogs who hardly exist anymore, in the All-Ireland semi-final.
Three years earlier Tyrone arrived in the final against Kerry having already played three ferocious games against Armagh and two against Dublin. If ever a team had been tested in the fire it was Tyrone in 2005.
Even their triumphant 2003 All-Ireland campaign included the nerve-wracking draw against Down which prompted Mickey Harte to make the crucial redeployment of Cormac McAnallen to full-back.
Those trying campaigns suited Tyrone because they brought into play Harte's great knack for improvisation.
The McAnallen switch is perhaps the most notable example, the moving of Seán Cavanagh to full-forward in 2008 is another, while Joe McMahon and Enda McGinley found themselves perpetually and efficiently on the move as Harte chopped and changed assiduously throughout the glory years.
In 2008 the team which played in the All-Ireland final had five personnel changes from the team defeated by Down and only the full-forward line was exempt from positional switches.
Few managers have been as willing as Harte was back then to make a shrewd reappraisal in the face of adversity.
The problem for him today is that there hasn't been any adversity this year and if there are any weaknesses in the Tyrone line-up they will be ruthlessly and immediately exposed by the best team in the game.
You don't learn things gradually in the new shallow football championship, you learn them all at once and precisely when the penalty for failure is highest.
Take Pádraig Hampsey and Tiernan McCann for example. So far in the championship they've looked like two of the best all-round players in the country, playing a kind of Total Football from the half-back line, epitomised by the three points from play Hampsey landed in the Ulster final.
Yet how will they react when they are forced onto the back foot and have to cope with Ciarán Kilkenny running at them and the Dublin half-backs pouring forward at pace?
We don't know, and neither do we know how Ronan McNamee, outstanding so far this year, will cope with the Dublin full-forward line. Is he perhaps a little statuesque to deal with the likes of Con O'Callaghan, Paul Mannion and, before the day is out, Kevin McManamon?
For all the talk of the Tyrone defensive system there will come a time when McNamee and McCarron and Aidan McCrory are exposed on an individual basis. Can they cope as McAnallen, Ryan McMenamin and the McMahons, Justin and Joe, used to?
Colm Cavanagh has had the best championship season of an inconsistent inter-county career. There's no doubt he has the requisite physicality and energy to overcome Brian Fenton, but can he really do it when the pressure comes on against an opponent who thrives in big games?
Niall Sludden and Mark Bradley have been a joy to watch this summer but a ruthless Dublin defence will pose a kind of challenge they simply haven't encountered this year, and which can't really be prepared for on the training ground.
Perhaps most troubling, for all the impressive totals Tyrone have racked up this summer they lack an outstanding score-getter in the mould of Paul Geaney, Dean Rock or Cillian O'Connor.
Their top scorers in their last two games, both scoring two goals, were Ronan O'Neill and David Mulgrew, introduced as subs when the game was already won. Both players were underage prodigies but neither have taken to inter-county football with the alacrity of Con O'Callaghan.
If Tyrone win today they will need a couple of forwards to reach new heights and maybe Seán Cavanagh to reascend old ones too.
Most neutrals will hope those heights can be scaled because the football championship is in severe need of a new power. We will know after today if Tyrone fit the bill. One way or the other the mystery will be solved.
This is a vital day not just for the football championship but also for Mickey Harte.
It's been said that Tyrone have been too patient with their manager in recent years yet a man with his record deserves patience.
The narrow All-Ireland semi-final loss to Kerry in 2015 and the successive Ulster titles which have followed, Tyrone's first two-in-a-row since 2010, suggest he may have built another considerable team.
But can it be as good as the teams which used to roar over the border and sweep aside everything in their way, teams which at their best had an irresistible quality rarely witnessed in Gaelic football?
Or will this year be like 2010 when having looked utterly ominous in Ulster, Tyrone crumbled against the Dublin challenge in Croke Park and didn't recover for years? Is this Harte's last laugh or his last stand?
Really, you don't need pundits to call this one for you, you need Manuel from Fawlty Towers. Because until Dublin start really putting it up to Tyrone today, we know nothing.
This is the day when things fall into place.
Sunday Indo Sport