Tony Ward: World-class half-backs can swing this arm-wrestle our way
Sexton and Murray hold key to turning Cardiff hostility against Wales
The home of Welsh rugby in the heart of the Welsh capital is a stadium like no other on big match day. Roof on or off, the atmosphere in the Millennium Stadium is electric.
It is the greatest rugby stadium in world rugby.
From an Irish perspective the atmosphere will be hostile, but that provides an added incentive.
I wish this were a Saturday Six Nations game as in the days of yore. Instead what we have is a night match guaranteed to have the ground rocking - especially with the roof closed for what is a must-win match for both sides.
As with the France match a fortnight ago, I suspect it might not be overly pretty, but if the team in green can produce a similar level of performance, there will only be one outcome.
Orchestrated by Johnny Sexton and Conor Murray, what we witnessed in Dublin a fortnight ago was a team high on self-belief, never ever panicking when the scores refused to come.
That patience is a new departure for Ireland under Schmidt and I expect it to be at the heart of the game-plan again this evening.
The Welsh will come with all guns blazing. Losing to England in the manner they did was bad enough, but to follow that up with such a feeble effort at Murrayfield has ratcheted up the pressure on Alun Wyn Jones and this unchanged Welsh 23.
Howley has gone on the premise that this squad owes him one. They had better deliver or not only the interim coach but main man Warren Gatland (on sabbatical with the Lions) could be facing the chop were they to lose three Six Nations games in a row for the first time in a decade - and with the French in Paris still to come.
To that add the ugly thought of losing successive home matches in the same Championship season for the first time since 2003.
Given the crunch issue of ranking points ahead of the upcoming 2019 World Cup draw, Welsh backs are to the wall.
Ireland's record at the Millennium is pretty tasty, with six wins from the nine played, but each of those wins has been hard earned.
I suggested earlier in the week that the noise of the home crowd can be turned into an unwitting 16th man for the visitors.
At its simplest, Irish patience on the field will lead to Welsh impatience off it.
Tommy Bowe for the injured Andrew Trimble is the only change to either match 23 from the Aviva a fortnight ago.
Schmidt is a firm believer in acknowledging previous performances, particularly at away venues.
That plus Bowe's ability in the air gets him the nod ahead of Craig Gilroy and Andrew Conway as outside replacement back. Trimble and Bowe are peas from the same pod in that key aerial regard. Mind you, the Monaghan man can still attack a bit too.
For Schmidt, being able to put together back-to-back starting line ups is a luxury - he rightly points to the little improvements that can be made through increasing familiarity.
Indeed, despite the claims of Peter O'Mahony, Cian Healy and the soon to return Jared Payne, any change post-France would have been most unfair.
'If it ain't broke, don't fix it' is the appropriate course for a Welsh challenge riddled with danger.
Only in the back three do the hosts have a marked attacking advantage over their immediate opposites, although Simon Zebo would challenge for a place in Wales side were he Welsh qualified.
However, of that Welsh trio, only Liam Williams has been on song of late, with Lions Leigh Halfpenny and George North way undercooked in the two games of consequence to date.
If Ireland are to make it through to a title decider against England, then tonight's match will not be won out wide.
I am looking to the back-rows and half-backs.
In the back-row they have Sam Warburton, Justin Tipuric and Ross Moriarty, with Taulupe Faletau in reserve while we can match that with CJ Stander, Sean O'Brien and Jamie Heaslip backed by O'Mahony on the bench.
Primary possession is likely to be shared, but with a possible advantage to the Welsh at the tail of the lineout.
As ever it comes down to use of the ball, specifically by the halves.
In the championship to date Murray and Sexton (albeit in just his single appearance against the French) have been the most influential combination, with Rhys Webb second only to Murray as top scrum-half.
By contrast out-half Dan Biggar has been tepid - and that's being kind. The Welsh No 10 is now under pressure from Sam Davies for his place. But Biggar is a proven big-game performer, so this is his stage .
There is a little concern too about Wales matching us off the bench. Certainly in Faletau, Jamie Roberts and Luke Charteris, they have impact.
It really has all the makings of a cracker, and the travelling Irish fans are in for a great experience in Cardiff.
A nervous nod to Ireland by three.