Australia have the chance to put England through hell with an early exit from their own Rugby World Cup when the two sides meet on Saturday.
How sweet would that taste across the other side of the world – spoiling England's big party by knocking them out and creating history in the process.
No host nation has ever failed to make the quarter-finals, and England are standing right on the edge of the cliff.
Two games in six days has meant that Michael Cheika had to chop and change his side but there's no mistaking that Saturday's XV is his strongest available.
Less than a year ago Australia were dominated up front by England's scrum but since then under the tutelage of Mario Ledesma they are no longer a soft touch. In fact, their 94 percent scrum success rate in the Rugby Championship was some way ahead of South Africa and Argentina.
Australia had to act after that pummelling at Twickenham and Cheika's move to bring in Ledesma now looks golden. Disspelling the myth that the Wallabies are a soft touch at scrum-time might take many years, but Ledesma's passion and experience – found in his playing days slotted next to the likes of Rodrigo Roncero and Martin Scelzo – have had a clear effect.
Get the platform right and the damage the backs can cause for the Wallabies is limitless, even if there are some doubts. Will Genia's rise from third-choice scrum-half to start throughout the year has gone under the radar.
His half-back partner on Saturday, Bernard Foley, was the outstanding player in Super Rugby in 2014, but he hasn't hit those heights this year and especially with his goalkicking which has gone from excellent to inconsistent. Dan Biggar has already proven how important every three points can be in tight Tests such as Saturday's.
That said, Australia have to be respected for winning the Rugby Championship. Their belief to hang in when behind against South Africa and then to achieve a first Test win over New Zealand for four years shows how far Cheika has brought a side that felt lost in the latter days of Ewen McKenzie's reign.
Australia have an array talents unafraid to take risks – including Israel Folau, Adam Ashley-Cooper and Matt Giteau – but importantly Cheika has installed both a focus and drive into this team who now don't know when they're beaten.
England won't have lacked for determination this week, desperate to put last weekend's crushing loss behind them.
Chris Robshaw's role as England captain always means he will be in the firing line, but the level of over-the-top criticism chucked at him over the last week has been unreasonable.
If England score the try they needed, he's hailed as a bold leader. If Owen Farrell misses the penalty from out wide, or even converts it to maybe set up a draw, then Robshaw lacks the guts of say Japan's Michael Leitch to put it all on the line and go for the win. He can never please everybody – especially when the ramifications are so high.
England's lineout lacked the bravery of Robshaw's call, a gift to the front, and here they are a week on fighting to stay in a World Cup held on their own turf. Stuart Lancaster will have prepared the scenario, but that doesn't make it any less of a nightmare.
He and his players are under unprecedented pressure – playing for their reputations, careers and under the pressure of an expectant nation. Frankly, it will make or break them.
The loss of Billy Vunipola is serious considering his performances since he was dropped last November and how he has played in 2015, although Ben Morgan rarely lets his country down. Joe Launchbury meanwhile starts only his second Test since England's 2014 tour of New Zealand.
But the major return is Jonathan Joseph. Nothing was secret about England's midfield masterplan against Wales and until Biggar and co recognised the space outside a muddling Brad Barritt's 13 channel, they more or less held firm. Sam Burgess has been panned for his lack of positional intelligence and route-one approach – what a shock after only four Tests and less than a year in the sport – but he was hardly the architect of England's downfall and some of the slurs thrown his way have been excessive.
Joseph though is England's key, a distributor with enough pace and footwork to open up defences on his own. He gives England balance and the ability to get wider, faster. Had he been ruled out by the pectoral injury that saw him miss the game with Wales, then England's chances would be even slimmer.
He returns just when England need him most – when they need everything to go their way. Three wins out of four against Australia at Twickenham since 2010 – including a 20-14 loss – point logically towards success.
But if England once again achieve supremacy on the scoreboard, they now know the price of failing to keep the door shut, and at what a cost.
Saturday was always going to be a blockbuster. Now it feels above and beyond that. We will never see another Rugby World Cup group game with as much at stake.
Ones to Watch
For England: His fitness wasn't guaranteed until Friday but Ben Youngs being healthy enough to start is huge news for England, because as soon as he left the field against Wales, the hosts began to unravel. Youngs has been the standout scrum-half for England for years and repaid Lancaster's faith, four years after he travelled to the Rugby World Cup as one of England's youngest players. Now with over 50 caps, England will rely on him in attack and their kicking game.
For Australia: Few players graft as hard Scott Fardy, the giant blindside flanker who essentially gives the Wallabies an extra lock and the necessary physicality to balance out the Australian back row. It's hard to believe that Fardy only played his first full Super Rugby season in 2012 based on how quickly he has risen to the top of the game in Australia, but he has made himself essential to the national side.
Head-to-head: Two key battles will settle Saturday's game – the breakdown and the scrum. Tom Wood and Chris Robshaw aren't flankers in the same style as Michael Hooper and David Pocock but they have to contain the Australian duo and stop them from dominating at the breakdown otherwise the Wallabies will control the penalty count and territory. You can bet that England have been working on their counter-rucking. Pocock is also the key to Australia's impressive rolling maul.
Meanwhile up front Joe Marler and Dan Cole take on Sekope Kepu and Scott Sio after a week's worth of discussion on scrum angling and how Romain Poite will referee the set-piece. Sio has kicked on in 2015 after not being part of the Wallabies 23 last November, and he looked confident against Uruguay. Cole though will be another level. Kepu has also made strides under Ledesma and Marler, whose every position will be scrutinised in the early engagement, can test how far he has come since being subbed after 50 minutes when the two sides last met.
2014: England won 26-17 at Twickenham
2013: England won 20-13 at Twickenham
2012: Australia won 20-14 at Twickenham
2010: England won 35-18 at Twickenham
2010: England won 21-20 in Sydney
2010: Australia won 27-17 in Perth
Prediction: Forget the Wallabies' recent record at Twickenham; they are more than good enough to take this one with their personnel – and with Israel Folau ready to cut loose – but to win they will have to back up the notion that they are far more competent in the scrum compared to a year ago.
England though are completely desperate for this victory, aware of the black hole that awaits on the other side of this game if they slip up again. That fear take them to another level when they'll need it most. England will have to be more clinical, because the stakes have never been higher and Lancaster's job, along with Robshaw's captaincy, are on the line. England by 3.
England: 15 Mike Brown, 14 Anthony Watson, 13 Jonathan Joseph, 12 Brad Barritt, 11 Jonny May, 10 Owen Farrell, 9 Ben Youngs, 8 Ben Morgan, 7 Chris Robshaw (c), 6 Tom Wood, 5 Geoff Parling, 4 Joe Launchbury, 3 Dan Cole, 2 Tom Youngs, 1 Joe Marler
Replacements: 16 Rob Webber, 17 Mako Vunipola, 18 Kieran Brookes, 19 George Kruis, 20 Nick Easter, 21 Richard Wigglesworth, 22 George Ford, 23 Sam Burgess
Australia: 15 Israel Folau, 14 Adam Ashley-Cooper, 13 Tevita Kuridrani, 12 Matt Giteau, 11 Rob Horne, 10 Bernard Foley, 9 Will Genia, 8 David Pocock, 7 Michael Hooper, 6 Scott Fardy, 5 Rob Simmons, 4 Kane Douglas, 3 Sekope Kepu, 2 Stephen Moore (c), 1 Scott Sio.
Replacements: 16 Tatafu Polota-Nau, 17 James Slipper, 18 Greg Holmes, 19 Dean Mumm, 20 Ben McCalman, 21 Nick Phipps, 22 Matt Toomua, 23 Kurtley Beale
Date: Saturday, October 3
Kick-off: 20:00 local (19:00 GMT)
Referee: Romain Poite (France)
Assistant Referees: George Clancy (Ireland), Marius Mitrea (Italy)
TMO: Shaun Veldsman (South Africa)