If there is any trepidation for Ireland in their moment of unprecedented World Cup triumph, it is the knowledge that raw emotion played a part in their demolition of the tournament's second favourites in Auckland. Now that the injured hooker Jerry Flannery has gone home – having done his bit by handing the jerseys out for this thunderously entertaining pool win over Australia with tears in his eyes and words of encouragement stuck in his throat – they might need to find another extraneous influence to raise the same pitch again.
However they do it, the next steps must be to ease past Russia this weekend and then let the mightily impressive back row of Stephen Ferris, Sean O'Brien and Jamie Heaslip loose again in the final pool match with Italy on Sunday week and head into the quarter-finals as Pool C winners with momentum to boot.
Jonny Sexton, the Ireland fly-half, needs to sharpen his goal-kicking but his daring in attack was evident in this first World Cup win over Australia in five attempts; a first Irish win over any of the big five (the Tri Nations, England and France) since the tournament began in 1987.
"I suppose we kept telling ourselves that it was coming," said the Leinster No 10. "We lost our warm-up matches but we knew the coaches were changing the team every week, getting 25 players fit. This was probably our most special day in green jerseys for a lot of us. But this can't be our final. This can't be our World Cup now, we've got to go out and get to a quarter-final and take it from there. Once you get to a quarter-final anything can happen."
Sexton and the eight other Leinster players in Ireland's XV should know, having captured two Heineken Cups in the past three seasons in a competition with a similar format to this one. Ireland looked every bit a team who knew their game plan, and that of Australia's, whereas the reverse could not be said of the wobbly Wallabies. They were frustrated initially by Ireland's habit – well-known in Six Nations circles – of tackling the ball-carrier and turning him over by keeping the ball in a maul.
Ireland also prospered in the scrummage and earned a handful of penalties, which was less of a shock. The late cry-offs of Australia's star openside flanker David Pocock and hooker Stephen Moore dotted the i and crossed the t for a famous Irish victory.
"It isn't the end of the road for us," said Quade Cooper, the Australia fly-half, whose ludicrous behind-the-back pass intercepted by Tommy Bowe three minutes from time was the last straw for the Wallabies. "It just makes the road tougher."
And indeed it was the buzz of both the North and South islands that the draw for the knockout rounds might now settle into one half populated by Six Nations sides – Ireland versus Wales, and England versus France quarter-finals, with the other including all the Tri Nations. One out of Australia and South Africa (the teams ranked second and third in the world) look like departing in the last eight, as they are likely to meet in Wellington on 9 October.
Australia have gone 25 years without a win at Eden Park, and although Cooper – who was born in Auckland and raised in the Waikato – observed that "a ground's just a ground" it's an uncomfortable fact for the Wallabies that this particular ground is where the business end of the competition will be played. Cooper's brilliantly creative tendencies put his side in trouble a couple of times. Shall we cut his side some slack? Australia have a youthful squad among whom 22 of the 30 are playing in their first World Cup and maybe they are not as fully formed as their status as Tri Nations champion suggests.
The Irish, by contrast, had 34-year-old Ronan O'Gara to guide them home with two penalty goals after he came on for the hamstrung Gordon D'Arcy, to add to Sexton's two penalties and a dropped goal in reply to James O'Connor's two penalties.
Afterwards, O'Gara hinted in a television interview that he would finish his Test career after the World Cup. Perhaps that will be the next well of emotion plumbed by the pumped-up Irish.
Scorers: Australia: Penalties O'Connor 2; Ireland: Penalties Sexton 2, O'Gara 2; Drop-goal Sexton.
Australia: K Beale; J O'Connor, A Fainga'a (D Mitchell, 74), P McCabe, A Ashley-Cooper; Q Cooper, W Genia; S Kepu, T Polota Nau, B Alexander (J Slipper, 61), D Vickerman (R Simmons, 61), J Horwill (capt), R Elsom (W Palu, 72), R Samo (S Higginbotham, 74) B McCalman.
Ireland: R Kearney (A Trimble 74); T Bowe, B O'Driscoll (capt, A Trimble, 59-62), G D'Arcy ) O'Gara, 49), K Earls; J Sexton, E Reddan (C Murray, 57); C Healy, R Best, M Ross (T Court, 76), D O'Callaghan, P O'Connell, S Ferris, J Heaslip, S O'Brien.
Referee: B Lawrence (New Zealand).