The aftershock from Ireland's seismic series victory over the All Blacks will be felt all the way to the Rugby World Cup in France next year.
Coupled with England's dogged series win over Australia and the impressive performances of Wales and Scotland against South Africa and Argentina respectively, next year's tournament is shaping up to be the most competitive there has ever been, which is so exciting for the supporters and brilliant for the game.
And there is genuine cause for belief that for the first time since England were crowned champions in 2003, the Webb Ellis trophy will remain in the northern hemisphere.
France, as hosts, will be many people's favourites, but Ireland's historic triumph is a game-changer. Ireland have never made it beyond the quarter-finals of a World Cup, but Andy Farrell's team look equipped to be considered as genuine contenders to win it.
The size of the achievement of winning a series in New Zealand cannot be overestimated, even if the All Blacks have lost their way a little over the last year, and the biggest impact will be a psychological one. World Cups have often tested the mental strength of the Celtic nations when they are labelled as favourites.
At the 2011 tournament, when I was Wales head coach, we came up against an Ireland side in the quarter-finals who had been tipped for great things after defeating Australia in the pool stages. All the expectation was on Declan Kidney's team, whereas we had reached the knockout stages without much fanfare. But I knew we could use that to our benefit by constructing a game plan to frustrate Ireland and ramp up the pressure on them.
Ronan O'Gara's kicking was central to Ireland's game plan, so for the first time we deployed two full-backs to drop back from the defensive line and cover both touch lines. Back then it was normally left to the full-back to cover the back field, sweeping left or right, but we felt it was worth the risk to drop two men back to cut off the space and options for O'Gara.
We also swapped around our wings, Shane Williams and George North, just before the kick-off, as we knew that Ireland would have a specific plan to target Shane, who is 5ft 7in, aerially. Shane was named on the left wing but played on the right. It worked a treat. Allied with our mammoth defensive effort, Ireland just wilted under the pressure and were not able to adapt tactically. Our 22-10 victory was one of the finest performances of my tenure as head coach, and one of the most satisfying.
Yet what I saw from Farrell's side on Saturday was a complete contrast. Ireland looked brilliantly coached, with a game plan that exploited the All Blacks' weaknesses, and which was backed up by ferocious commitment and mental robustness.
Even in their current state, New Zealand remain a team who can score 15 or 20 points from nowhere, and if they build a lead are phenomenally difficult to catch. Ireland knew that and once again started stronger and out-scored them in the first quarter. They then had the wherewithal, confidence, and game management to cope with the backlash just after half-time and go again. Ireland squeezed them and it was remarkable to witness them finishing comfortably in control.
They now have a year to come to terms with the expectation, but the biggest challenge now is to ensure there is a match-ready back-up to Johnny Sexton. He had an outstanding series but will be 38 by the time of the World Cup. The likes of Joey Carbery must now be given the chance to start this autumn.
It will take a tough conversation with Johnny, who wants to play in every game, but Ireland cannot afford a repeat of 2019, when his unavailability against Japan was critical to their pool defeat.
The same logic, but for different reasons, applies to England fly-half Marcus Smith. At a dinner on Friday night I was asked what I thought of the Harlequins player. I surprised the questioner, who it turned out was not a fan, by saying I think he has the ability to become a world-class fly-half.
There were glimpses again of his potential in England's third test victory, and I liked the way he has been playing flatter and being more involved at first receiver.
What Marcus needs now, more than anything, is a run of test matches to build his confidence and experience. When a player first breaks on to the international stage, particularly in a decision-making position, test matches are like watching a movie in fast forward.
The images in front of the player flash by in contrast to the speed of the game he is used to at club or provincial level. Yet with every test match they play, gradually the pictures become slower and the clarity grows. It is something that cannot be coached. All that Marcus needs now is games. What impressed me on Saturday is that Australia tried to run down his channel and he stood up and was counted. By the time of the World Cup, he could be seeing the game in slow motion, and without wanting to disappoint my dinner guest, that is a frightening prospect for England's opponents.
Eddie Jones will have been delighted to clinch the series. Australia dominated possession and territory but England showed real grit and determination to grind out the win, led superbly by Courtney Lawes. I was so impressed by his character on the Lions tour last year and if I was Eddie, he would be my man to captain England to the World Cup now. I was impressed too with how the new faces Guy Porter, Jack van Poortvliet and Tommy Freeman came through. England have finished the tour with more options and can now kick on during the autumn.
Although Wales and Scotland lost their respective final tests against South Africa and Argentina, both camps have also taken big strides this summer, which left me thinking about how difficult it would be to pick a Lions XV a year on from our tour to South Africa.
Well, just for fun I am going to give it a go and will get back to you shortly. In the meantime, why don't you have a go yourself... it is not as easy as it looks!