And a decider it decidedly is. If Ireland lose this match they are effectively out of contention in the tournament. If Ireland win it, then the sun comes out again and we all look forward to hosting a France team that could be in any kind of shape by the time they reach us.
Kidney has always retained the capacity to throw in a wildcard or two. We'll always have the Tomas O'Leary and Denis Hurley introductions ahead of Peter Stringer and Shaun Payne for a Heineken semi-final to produce as evidence here.
And Paddy Jackson ahead of Ronan O'Gara has to go down as a wildcard. Luke Marshall is only marginally less so, ahead of several other options available to him such as Fergus McFadden; or moving Keith Earls into second centre and Brian O'Driscoll into first; or likewise with Luke Fitzgerald. Particularly given how little game time Marshall has had of late. However, the stratagem of using O'Driscoll has been tried before and never really come off.
So whatever he did, I think Kidney would have added weight to the option of not moving the talisman.
The leapfrogging of Tom Court to start ahead of David Kilcoyne has also caused some raised eyebrows. The thinking here must be that Kilcoyne was on the bench as the greater impact player, given his more dynamic ball-carrying ability. But, as a more solid scrummager, Court has been deemed the more reliable starter. For me, this is a good decision that rewards Court for his exceptional season to date.
Even Donncha O'Callaghan ahead of Devin Toner may have caused some debate, given how the lineout malfunctioned in the early part of the English game, and Scotland's relative strength in that department. However, with the power of the Scotland pack (not to be underestimated) O'Callaghan's greater presence at ruck and scrum time is an understandable preference.
But all else pales by comparison with the call at Number 10. If I'm honest, I thought Ian Keatley might have been the shot to play. In my view, he represents the mid-point between Jackson and Madigan. Keatley is a little more mature than either, is a decent game manager, offers a personal threat on the gainline, is solid in defence and is a very respectable place kicker.
Going with Jackson is high risk, especially as he will be without hisregular partner Pienaar, who takes a lot of pressure off him at Ulster both in terms of game management and placekicking. That said, it can be difficult for Jackson to take that pressure on himself in the presence of Pienaar, so he may actually revel in the additional responsibility being thrust on him. This, clearly, is Kidney's judgement.
I have always been quite impressed with his sang froid since first watching him for the Ireland Under-20 side a couple of years ago. He displayed impressive coolness under pressure as a younger man then and was very reliable. With a couple of years professional rugby under his belt, he should be able to handle the occasion.
It's quite an ask of newly-installed captain, Jamie Heaslip, to lead this now almost callow looking side into the home of a nascent Scottish resurgence.
Though he made a couple of high-profile handling errors, there was one moment in the English match that was quite brilliant from Heaslip. Midway through the first half an Irish attack on the English 22 came a cropper and the English fly-hacked ahead deep into Ireland's 22.
Rob Kearney came racing back and went down on the ball as Ashton and another couple of English players bore down on him. The replay showed however, that Heaslip took off from close to where the Irish attack broke down, showing tremendous pace to arrive not much later than Kearney and miles ahead of any other Irish player. He shored up the breakdown until cover arrived and Ireland survived a potential try scoring opportunity for England.
What impressed as much as the pace to get there was the early recognition of the danger and the will to get there, both of which were in marked contrast to a number of Irish players similarly placed at the outset. I expect Heaslip to have a big game, based on his innate self-confidence.
Listening to Matt Cooper yesterday evening interviewing Alan Quinlan about this selection, I was astonished to hear him ask if Kidney's selection wasn't as much down to Scotland not being a very good side as anything else. In other words, if this was Kidney experimenting with selection because he could afford to.
Maybe it's because I have sat in Murrayfield quite a number of times pre-2001 when we had our collective arses handed to us on a plate, and maybe he was being deliberately provocative (though I think there are indeed many out there who think like this), but I have a real sense of trepidation about this one. Their coaching ticket is a canny one and in Hogg and Maitland they may finally have discovered the couple of extra pieces that transform the whole from staid to incisive.
Ireland are 4/6 at the bookmakers, which you'd have to say recognises that Scotland showed an attacking threat against Italy not seen for some time and have a beast of a pack. Not the kind of odds that would induce a relative conservative to start swinging from the hip.
If nothing else, Kidney deserves some credit for his bravery with his selection of a side that is geared for the future. As William Wallace said in Braveheart, 'Every man dies. Not every man really lives.'