Six Nations analysis: Ireland's mission is to keep final day title dream alive
Failure to beat Wales in Cardiff would ensure a St Patrick's Day damp squib against England
Ireland will need more than clear eyes and full hearts under these Friday night lights. With the roof closed at the Millennium Stadium, Wales' backs are against the walls and the locals are demanding a performance.
Come 8.05 tonight, Cardiff will be heaving and the arena will feel claustrophobic. The home side need to rescue their season, Ireland are looking to keep theirs alive.
Over the course of the next two matches, we will find out more about Joe Schmidt's team than we did in November.
All of the progress against New Zealand and Australia will be undermined by a disappointing spring campaign. Schmidt came into the Six Nations targeting a top-two finish and a loss tonight would be utterly deflating.
Defeat to Scotland on the opening day reduced their margin for error and for the third successive game their season is on the line.
The final day clash with England has loomed large on the calendar for months now and they know it would be a terrible shame to go into it with nothing but pride to play for.
If Eddie Jones' men can overcome their penultimate hurdle against Scotland tomorrow, they will be chasing back-to-back Grand Slams and a world record 19th Test win in a row.
In the past, stopping those bits of history would be enough for Ireland but the days of being happy with upsetting the old enemy have long since passed.
If Ireland want to be considered a world-class team on their own merits, then they need to be competing for their third Six Nations in four years tomorrow week.
Whatever satisfaction Ireland take from denying Jones' men would be tempered by the sight of them lifting the title regardless.
The autumnal success over New Zealand changed the dynamic for this Irish team. Over the course of a transitional 2016, Schmidt infused his squad with new blood but as the last of the World Cup casualties returned to the fold, the mix of old and new has left the Kiwi coach with a strong hand to choose from.
It has been a while since he's been able to name an unchanged starting XV or choose from all of his centrally contracted star players.
Of the main IRFU employees, Jared Payne is the only one to miss out and if he comes through for Ulster tomorrow he is likely to come on to the bench next weekend. So, there are no excuses at the outset of a fascinating game.
With Johnny Sexton back operating in tandem with Conor Murray, Ireland have a half-back partnership that has the measure of any opponent. Their pack is fearsome, their back-row as dynamic as any going and their backline can threaten with a range of options.
By choosing to play under a closed roof, there is a commitment to continuing the positive play that has underpinned the team since the summer tour of South Africa.
You won't hear the word bonus point mentioned, but it would be no surprise to see Rory Best (pictured) keep it in the back of his mind as he makes decisions over penalties.
Ireland's priority, however, is a win. With a comfortable points difference lead over England, they know a straightforward win will put them in position for final day. A bonus would be, just that, a bonus.
Wales may be struggling after losing to the English and Scotland, but they don't lose three on the trot very often.
It is telling that Rob Howley has tasked his experienced team with going again and some of those players know their Lions tour is on the line. For some, it may even be about their international futures.
Warren Gatland will watch on from the stands having visited the camp last weekend and his presence undoubtedly adds another layer of pressure.
"Each individual deals with it differently. There's still a level of hurt there from the Scottish defeat and I'm sure players are feeling that as well," coach Robin McBryde said yesterday.
"We need to react in a positive manner in the opening stages with what will be a very confident Irish team."
It is up to the Irish to ensure that it is the home team who feel that burden.
Since the Scotland game, both George North and Leigh Halfpenny's form have been the subject of very public debate, with even the coaching staff getting involved in the discussion.
World-class players when in form, that's two-third of the Welsh back-three who are under real scrutiny, while Liam Williams is brilliant going forward but has made big errors in defence.
It would be no surprise to see Ireland attack the wide channels, but if Wales want to succeed they might follow suit, especially in the wake of comment from Scotland attack coach Jason O'Halloran, who yesterday outlined his strategy in unlocking Andy Farrell's rearguard.
Indeed, given the issues Ireland had in this regard during the World Cup, the highly-rated New Zealander's comments will be disconcerting for the management.
"Our analysis said that Ireland get quite tight with their defence and we could beat them for pace on the outside," he said as he explained his side's success. Wales may well take note.
For all of that, Howley's men simply haven't been scoring tries. Against Scotland and England they created opportunities, but then butchered them.
The fear for Ireland is that they'll click tonight.
With the momentum of a partisan, well-oiled home crowd behind them there is a chance that the tide can turn but there is also plenty of unrest among the natives and if Ireland can get ahead early on then they can use the crowd to their favour and exploit the Welsh doubt.
Up front, Schmidt is looking from a stable, playable scrum and clean lineout ball. Two years ago, the men in red were able to disrupt Best's throw, and given Ireland's reliance on possession from touch for so much of their scores it is imperative they can secure their set-piece.
Murray and Sexton will undoubtedly look to the air to test the brittle Welsh back-three, but it would also be no surprise to see the all-conquering Ireland back-row taking the game to their hosts in their own inimitable style.
CJ Stander, Sean O'Brien and Jamie Heaslip - who wins his 100th Test cap - have the capacity to break the line and put the red jerseys on the back foot, while Peter O'Mahony, Iain Henderson and Cian Healy can sustain the tempo when introduced.
Experience will count for little given Wales have a collective 714 caps between them and Ireland 715. These are two sets of players who have seen it all and done it many times.
Wayne Barnes will play a role and Schmidt will have drilled into his players the importance of playing the English referee who played such a pivotal role two years ago.
There is a growing confidence about Ireland who are improving as the Championship progresses. Sexton's health is key to their well-being and if he has a big game it will go some way to winning the match.
England linger on the horizon as the perfect finish to what has been a memorable Six Nations so far.
Yet when 8.05 rolls around and the cacophony of noise builds towards Land of our Fathers beneath the roof, there will only be one show in town.
Getting out of Cardiff with the desired result is the mission for Best and his team who will fancy their chances of turning England over at the Aviva Stadium.
Whether the title will be on the line remains up to them and their ability to deliver beneath the lights tonight.