With brains, brawn and Gatland's planning, Grand Slam winning Wales will fear nobody at the World Cup

Paul 'Bobby' Stridgeon, the national physical performance manager, reached for his phone and recorded a video with a beaming defence coach Shaun Edwards.

Two leading architects of the Six Nations clean sweep had a well-deserved moment of celebration together, perhaps made all the sweeter by a Thursday jibe.

If Eddie Jones' barb about weary legs was made with the intention of making Wales wobble then the words were wasted; confidence in the squad's fitness has been a constant of the Warren Gatland regime and goes hand in hand with their snarling defence.

"We work very hard on it," said Edwards afterwards when asked about a defence that limited Ireland to a consolation try when the clock was in the red. "It's aligned to our fitness.

"In those down weeks the guys went through hell, particularly the down week before England."

So, while the English and Jones were preparing for the Calcutta Cup, Wales were already on the Champagne after showing no signs of tiredness.

Occasionally in the Gatland regime, when falling to defeat against southern hemisphere big guns, there have been times when you wondered whether brawn and fitness was all they had, yet this is a Wales side that is also well-tuned in the top two inches.

Against France, England and Scotland they had to show mental strength as well as physical power – in Paris they stayed calm to make a remarkable comeback, against England they knew to have confidence that they would come on strong when their visitors flagged, at Murrayfield they dug in when under the pump.

Remarkably, mental resolve wasn't needed against Ireland in the second half.

A fast start meant that cool heads were needed and Wales got the job done with maturity, their discipline not only keeping the champions at bay but stretching further away through the boot of Gareth Anscombe.

Wales' key moments in the championship came from winning the collisions – rugby can be a simple sport – but they have also had their strategies spot-on with the coaches helping them be tactically shrewd.

"We are a team, we are tight together like a family in a way," said Edwards about the management group.

"We have our arguments and don't agree on everything, we have our little fall outs every now and then, but you see what the end product is."

Wales are number two in the world because there is no longer a glaring weakness in their game.

This was a Grand Slam built by Gatland's empowerment, both of his management team and those that take to the field.

"Early in the week I said to the players whatever you want this week whatever you need to get you prepared for this game, everyone is here for you to do that," said Gatland post-match.

There is a confidence that stems from how the New Zealander operates in the week with players put through the wringer on the training paddock for good reason.

Every other nation will be working as hard – if not, why not? – but the boss tells his charges there is no chance they could be.

"We went to dark places together as a squad and that showed out there against England when we got the upper hand in the last 20 minutes – we felt that we could kick on while they looked pretty tired," said Dragons captain Cory Hill before the Ireland game.

"We've had that same intensity in training this week and the boys have a real edge about them."

Gatland's record also gives his players a lift. Rarely has he lost on the big occasion whether with Wasps, Wales or the Lions.

He now has three Grand Slams (plus his side won a title while Rob Howley held the reins ahead of the Lions tour to South Africa in 2013) and won 43 of 50 games in the Six Nations.

Wales have won 14 straight Tests and even if, as is likely, they come a cropper in the summer tune-ups against England and Ireland, two clashes in Cardiff and trips to Twickenham and the Aviva Stadium, they will head to the World Cup with the knowledge that they can win it. The All Blacks, who they haven't played since 2017, are the only other contender that they haven't beaten in the 14-game streak.

In October Gatland invited a group of over 60 players to the Vale Resort to talk about preparations for Japan, although so strong have the performances been since then that a number of those individuals know deep-down that they won't be going.

The meeting at Wales' training base featured a breakdown of the meticulous planning to ensure they give themselves the best possible crack at it being Alun Wyn Jones that lifts the Webb Ellis Trophy aloft in Yokohama at the start of November.

Knowing Gatland, it wouldn't be a surprise if he had planned for having to rip up the plan because of a Grand Slam.

"We do a review after every campaign as a management team and go through as a whole what we have done," he said.

"We are meeting as a staff on Tuesday and we have cancelled that. We are meeting for lunch now and a long afternoon because it is our last time together and there is nothing to review of the Six Nations.

"I can sum it up in two words: pretty good. That's the review over."