Let's be in no doubt - Ireland can expect a serious backlashes in Cardiff tonight. The famous ground will have it's roof closed and be packed to the rafters with expectant Welsh fans who, after two recent losses, will be demanding a home win.
Joe Schmidt has already experienced what it's like to face a team with only one thing on their mind when he took on a wounded All Black side in the Aviva two weeks after creating history in Chicago.
Tonight will be just as intense, and in my opinion the secret to an Irish victory is how the Irish coach and his players deal with the opening quarter of the match.
Before the disappointing opening round loss to Scotland, this weekend's clash against Wales was the game that many rugby pundits believed would ultimately determine Ireland's fate in this year's Championship.
In many ways it still does. If Ireland win then it leaves them in a great position to challenge for the championship against England on the last day of the competition, depending on what happens in the annual Calcutta Cup match between Scotland and England tomorrow.
If Ireland and England both win, then the final game could well come down to points differential and in this regard Italy did Ireland a major favour by keeping the score-line more than respectable in Twickenham.
Ireland need to take advantage by defeating Wales first. Schmidt will be under no illusion about what to expect tonight, and it is how he manages the opening quarter of the match that could determine the result.
Wales are in an unenviable position. A loss to Scotland, huge expectation of a rugby-mad country and the fact that if Wales lose this match, and the next one in Paris against France, then they will probably find themselves in another pool of death come the next next World Cup.
This effectively meant that under-pressure Welsh coach Rob Howley was not prepared to experiment with his selection for this match, and like Schmidt has named an unchanged side. The only difference is that Howley, unlike Schmidt, is coming off a loss.
Ireland can expect an early backlash in terms of intensity and physicality, but sometimes that can work against a team as well, especially if Wales do not score early.
Nerves are great in sport, but adrenaline runs out pretty quickly and can take its toll on mind and body if it involves too much prolonged anxiety.
The golden rule for Schmidt's men is to remain calm during the opening 20 minutes, expect the onslaught and prepare tactically for it.
Of course, for Wales it's the opposite approach. They need to score first, get confidence and continue to heap the pressure on Ireland. I have serious doubts if Wales have the firepower in certain areas to beat Ireland, especially in the set-pieces and fringe defence, and in my opinion Howley has not selected his strongest side, rather relying on loyalty and hoping that his team responds to him after the loss to Scotland.
Against England, Howley foolishly subbed two of his best players, scrum-half Rhys Webb and No 8 Ross Moriarty, too early. Together with a poor exit strategy, Wales suddenly saw England come back and snatch a late win.
It seemed that the decision had been made before the game as to when these players would be subbed and I think that is always a mistake. If I was Howley I would have looked to include experienced No 8 Toby Felatau against Ireland. Wales' policy of fielding two openside flankers in Sam Warburton and Justin Tipuric has not worked. It also leaves Wales without a third lineout option and at this stage, Wales' second phase play has not gone wide enough in recent games to justify incorporating two specialist opensides.
Wales, as they did under Warren Gatland in the 2011 World Cup, will know where to hurt Ireland, and will attempt to cut off Ireland's key ball-carriers like CJ Stander and Seán O'Brien immediately with the chop tackle, in the same way that Scotland did in the first half against Ireland.
But Ireland have far more than that in their arsenal nowadays, and the performances of the half-backs, Conor Murray (the best scrum-half in the world) and out-half Jonny Sexton, has been excellent.
Combine that with the power of Robbie Henshaw and the guile of Garry Ringrose and Ireland have a particularly strong axis in those areas.
Wales leaked far too many tries around the fringes against Scotland so they will have looked at that. Ireland may look at attacking slightly wider, as they did against France with Sexton looping well and create more innovation in the opposition 22, where Ireland are still guilty of becoming a bit tight and predictable.
Tradition dictates that Wales won't change much tactically - they can't. Dan Biggar will use the high ball to test the Irish wingers early and they will try to use their crash runners in the middle of the park. Wales also prefer to use the short side of the field a lot before coming back open and that means Ireland need to number correctly in defence.
Wales will defend a lot more aggressively than France in the backline. The French prefer to leave space on the outsides and then cover across, whereas Wales have always defended strongly from the outside in, pushing their big centres and wingers up hard and fast, trying to turn the Irish play back in. Ireland to win by eight.