Wales v Ireland: More than just victory on the line today as roof row encapsulates both teams' refusal to give an inch
A year ago, Ireland were approaching Twickenham with a bullet-proof confidence and, having put themselves in the position to win the Grand Slam, delivered the performance of their season to secure history.
Today, it is Wales' turn to roll into the Principality Stadium with the kind of confidence only a record-breaking winning-run gives a team.
Their aim is to end Ireland's tenure as champions with a victory that would propel them towards the World Cup with huge momentum.
Despite the status yellow weather warning, fans will descend on Cardiff for the party. Ireland's mission is to ruin it.
They've already upset the locals with their insistence that the stadium roof remain open tomorrow, regardless of the inclement conditions.
That decision could be viewed as an admission of weakness or a show of strength and it will invariably play into the post-match chat when the dust has settled. What it means is that the game will be played in wet, windy conditions which will test the skill-sets.
Schmidt clearly appears to be backing his forwards to get the better of their hosts; but is it foolish to give a team with such a proud defensive record that extra second to realign and come up at speed? Today will tell a lot.
It is the meeting of the teams ranked below New Zealand in the World Rugby rankings, a local derby between two sets of players who know each other well and two coaches who enjoy a frosty relationship.
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When they next play a competitive match, they'll be in Japan and starting an era-defining tournament. Getting today right and finishing the Six Nations on a high is vital.
On paper, Ireland are the better team.
Their team sheet contains a few players who can lay claim to being the best in their positions, they have starting Test Lions in key roles and boast a recent record to match any team.
Wales, meanwhile, are one of those teams that boasts a strong collective rather than a star-studded list of individual greats.
Their 13-game record winning run is impressive to a degree, but you can pick holes in the calibre of some of the opposition.They are on course to be the lowest scoring Grand Slam team in modern history and they have taken winning ugly to a new level.
But to underestimate them would be a grave mistake.
Their momentum is real, their defence is mean and their spirit is unquestionable.
Joe Schmidt is aiming for his first victory here as Ireland coach. His teams have arrived at the stadium and found the hostility of the crowd and intensity of the home team too much to handle.
He returns with a team that has faltered in this Six Nations, only to regain its composure and play its way into form.
Against France, they exerted total control and they fully believe that, if they can increase their intensity and stretch it out for 80 minutes, they'll win.
Captain Rory Best reckons that if they bring their best, it's good enough to beat anyone.
"We think it is. I think if you ask any of the top teams in the world they will say it is," he said. "But we feel that we've kind of shown it whenever we play to the best of our ability. And I think the exciting thing is there is more to come. And we have to show more.
"This has to be better than we've produced. But it's definitely in there. I think the top teams in the world are that, because that is their inherent belief that when they play to the best of their ability they win.
"And I think you saw a bit of that with the way we played against France at the start of the game. But in that Wales-Scotland game, in that second-half, even though Scotland were in the ascendancy, Wales always looked like a team who thought they were going to win.
"And I think that is something that you get with wins, with confidence, with being together.
"Certainly with the firepower we have, when we play to the best of our ability, we feel we are a handful for any team in the world."
So, where will this one be won?
All the indications are that this will be an intense affair with big collisions from the first whistle.
The conditions will see both teams tighten up, the aggressive defences will get off the line quickly and put pressure on ball-carriers dealing with a slippery ball. Both teams are confident in their scrums, while Ireland will use their fourth lineout caller in five games.
It is the first time James Ryan has had the honour. Best believes he'll be just fine.
"Yes, he is a reasonably young kid but it seems as if he has been around - with the performances he puts in - for an eternity," he said of the Leinster lock. "He hopefully will take it in his stride."
Securing clean ball out of touch will be key.
Tadhg Beirne will be tasked with bringing his energy around the park and breakdown threat to proceedings, while Seán O'Brien will fancy a shot at redemption and a reunion with Gatland to boot. If he can have an influence, then Ireland will be in a good place.
A big factor in Ireland's hesitant Six Nations campaign has been Conor Murray's slow service, and he needs to shake off his sluggishness.
He'll almost certainly kick more and Ireland's chase will need to be able to beat their way through the crowded shipping lanes to put pressure on the dangerous Welsh back three.
Alongside Murray, Johnny Sexton will need to exert control and his decision-making will be key. He has weapons outside him, but will have to choose his moment to unleash them wisely.
Both sides will look to maintain possession for long periods in enemy territory, but the wet ball may not help.
Shaun Edwards' defence has been impressively mean in this tournament and if they can hold their discipline they can frustrate the Irish backs.
Wales haven't been scoring too many tries, but when the chips were down against England they prodcued.
They have plenty of threats across their backline and can change things up by introducing Dan Biggar for Gareth Anscombe when the time is right.
At home, with a Grand Slam on the line and with Alun-Wyn Jones and Ken Owens at the helm up front, Wales will be confident of delivering their fourth Grand Slam in 14 years.
Ireland will be full of belief that they can spoil the party and at least put pressure on England, who are expected to beat Scotland in the final game of the day. If Ireland win and England lose, Schmidt's team retain their title.
More likely, they'll have to be content with a second-placed finish. The win in Cardiff would make it a decent enough recovery from the opening day defeat to Eddie Jones' side and a positive way to exit a tournament that started so disappointingly.
Wales have the momentum and the crowd, Ireland have lots of ability and are beginning to show form. It's perfectly poised.
THE SIX NATIONS PERMUTATIONS
Wales will win the title and Grand Slam if they beat Ireland.
Wales will win the title if they draw with Ireland and England lose to or draw with Scotland.
England will win the title if they beat Scotland and Wales lose to or draw with Ireland.
Ireland will win the title if they beat Wales and England lose to Scotland.
If Wales and England end up with 20 points each, Wales win the title as Grand Slam