It's less than a week until Wales and England clash at the Millennium Stadium and it's all getting a little bit psychological.
Warren Gatland made the first move in his press conference after he announced his Six Nations squad. The Kiwi suggested Stuart Lancaster didn't know what England's best side was. Then he laid down the gauntlet to England; dare they play under a closed Millennium Stadium roof?
Truth be told, there was little in the way of a challenge at all. It is true that with the roof closed the atmosphere in the Millennium Stadium could be measured in PSI, such is the pressure upon players. That pressure is too much for some to take; they crumble and crack. However, without pressure no diamonds would be made and - in a World Cup year especially - England need diamonds.
England lock Dave Attwood says he plans to block out the home crowd. However, the greatest players thrive in the hostility; they flourish in the inhospitable like lilies growing in the Baja desert. Will Greenwood has often spoke of the unique atmosphere of the Millennium Stadium and the true fondness he holds for it.
In 2001 Greenwood took part in the first Wales-England game to be played under the retractable roof and on top of the hallow turf. It's was Scott Gibbs 50th cap and the first time Wales had hosted the old enemy since he had broken English hearts in the Welsh 'home' game on English soil.
In an article for the Telegraph Greenwood said, "The stadium roof was shut, the crowd reacted like I have never heard before. It was the most incredible wave of noise bouncing around the stadium, and, as England players, we absolutely loved it."
Talking of being on the field before kick off that day Greenwood said, "Martin Johnson stood in the middle of our huddle with an enormous grin on his face, the rest of the lads smiling like Cheshire cats because you just know right then there is no other place in the world you would rather be." Greenwood silenced the vitriolic Welsh crowd that day with three tries as England ran rampant.
As much as the crowd will boost Wales and try to carry them over the line, so too the idea of silencing the partisan crowd should boost their rivals from across the bridge. Every boo, every cat call, every utterance of derision should fuel the fire in the belly of anyone with a red rose on their chest on Friday. It should spark the desire to silence every supporter in red that fill the stand and those outside the cauldron of the Millennium Stadium hoping and waiting on bragging rights.
The game's deciding factor will not be whom the support is for, merely who deals with it best. The pressure on both sides will be immense. This isn't a game; Wales-England is never a game.
However, this match is so much more too. It's not just present, it's past and future. Its more than the result; it is the springboard to Six Nations success and a prerequisite to the World Cup's group of death. It is historical, political and dutiful. Every player will carry that on their shoulders, but those that can carry the load of expectation from the assembled fans too will walk out the victors.
Clive Woodward told the Daily Mail that the secret to victory in Cardiff is to keep cool. Players must "tread the line between never taking a step backwards and not getting distracted or involved in anything that puts you or your team-mates off their game."
Last weekend we learned that serial offender Dylan Hartley has been seeing a psychologist to curb his infamous temper. Hartley has served suspensions for biting, gouging, striking opponents and swearing at an official. His reputation precedes him.
Such visits to sports psychologists and shrinks are hardly rare in modern sport; whether it be to combat aggression, depression or just mental attitude. However, Lancaster will weary of a red mist descending on Hartley as a Red Sea sweeps through the turnstiles of the Millennium Stadium.
The atmosphere on Friday will be fraught and not one for players with any mental frailties. If there are any cracks in Hartley's psyche, the Welsh players and fans will try to chip away at them. Mike Brown can expect similar treatment with his short fuse now infamous.
England have been preparing themselves for the Millennium Stadium with large speakers set up in training, but that will have about as much use as Usain Bolt preparing for the Olympics by racing his mother to the shops.
Gatland's challenge was little more than flimsily veiled mind games to remind England of their last visit to Cardiff. However, if England want to be taken seriously as World Cup contenders, it's a challenge they must accept. The pressure of winning a World Cup final in your own back yard won't be any easier just because it's your own fans applying it.
England's technical play has moved on massively since the 2013 defeat. However, Friday won't be a test of where their skill is at, as much as where is their mind?
The Pixies - Where Is My Mind?