This is it, then. Win or bust.
At least Wales know exactly what the equation is against England. No need to be cagey, play for draws and move on to the next game.
Anything other than victory in the Group B finale means Gareth Bale and his team will join one of Ecuador or Senegal as the first teams to fly home from Qatar, way earlier than manager Rob Page, his players, or the Red Wall anticipated.
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Even then Wales will need the USA and Iran to draw their own clash which takes place simultaneously, but they can only control what is in front of them whilst keeping tabs on what is happening elsewhere.
Mission impossible? Let's just say England have the wood on Wales, having won the last six fixtures between the two old footballing rivals.
They possess the better players, have greater momentum, are expected to top the group - there would be a firestorm to match any other in the English media if they lose to little old Wales.
But... Buster Douglas v Mike Tyson, Wimbledon winning the FA Cup, Japan stunning the Springboks at the Rugby World Cup. Every so often a seismic upset can happen. The unpredictability of sport is the very essence of what makes it so great.
The expectation levels aren't as high for Page and his team as they are for Southgate's England, it's more hope over reality. But that doesn't mean the manager of Wales shouldn't be under scrutiny for some of his decision-making at this tournament. The best way to be fully supportive of a side is to be constructively critical when things are going wrong.
And we can each agree they've gone pretty wrong for Wales thus far at the World Cup.
Not starting Kieffer Moore in the opener with the USA was a major blunder, putting Wales on the backfoot from the very start of the tournament when they really needed to hit the ground running after 64 years of hurt.
Bale, who else, got them out of a hole by winning and scoring a penalty. But when Kieffer was chosen to start the next game versus Iran, the right call, Page left out Dan James and Brennan Johnson, the very players with the pace required to run beyond the big man, stretch the Iranian defence and put over crosses.
Wales have been over-run too often in midfield, have been second-best to the ball at times, there are too many gaps in the defence and they've lacked real craft going forward.
That's a lot of things for Page to fix in such a short space of time. But we know these players are better than they are showing. We've seen that previously. Those issues can be sorted. The manager has to re-galvanise the players and devise a game plan which enables them to somehow shock England.
Page strongly hinted he was prepared to make major calls after the Iran shocker, taken by others to suggest the superstar duo of Gareth Bale and Aaron Ramsey might be dropped. That isn't going to happen, surely? Nor should it, in reality. Those two may have been terribly out of sorts by their lofty Wales standards, but they remain the duo most likely to provide the inspiration required to beat England.
If anything Page is more likely to treble down by starting Joe Allen as well as a third veteran, even though the Swansea man won't be happy with his role in Iran's two goals when he twice gave the ball away.
There are wildcard options Page will be considering. Starting Johnson is one of them, though at whose expense?
Ditching five at the back, his preferred method, and going with four to get one more creative force in the side is another.
He could stick with five and pick speed merchant Dan James as a right wing-back to offer Raheem Sterling and Luke Shaw down England's left-hand side something different to think about.
He could go the whole hog and ask mercurial Cardiff City talent Rubin Colwill to help knit the team together and provide the stardust that has been missing. But that's a huge ask of a 20-year-old.
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It's hard to see any of those things happening, in fact. Page is loyal to the core starters, it would be a surprise if he weren't one more time, and the truth is his options are somewhat limited anyway.
That said, other managers have definitely got the best out of the sum of the parts in their squads and this is the moment for Page to do so with Wales at this tournament, too.
Wales have not won in seven games under Page, indeed have only one victory in 10 to their name - albeit that was the one that really mattered at the time versus Ukraine. Whatever the standard of the opposition, and Wales have played some good sides during that run, that's a sequence of results that would put any international manager under scrutiny.
There is no better time for Page to turn the fortunes around than right here, right at this moment in time, the biggest stage of the lot in what would have to rank as Welsh football's greatest result in history.
Wales can't beat England, whatever formation and personnel the manager chooses, most of us will feel deep down. The odds are stacked heavily against. Yes, we know that.
Yet this is a tournament of shocks. Who would have forecast Japan beating Germany, Saudi Arabia stunning Argentina, dare I say it Iran overcoming Wales?
Morocco have just beaten Belgium, the number two ranked side in the world. Costa Rica, smashed for seven by Spain, then defeated Japan. South Korea drew with Uruguay, Ecuador fought out a stalemate with the hotly fancied Dutch.
Each of those results have completely thrown those wallchart predictions we were making before the tournament kicked off and the likely one-two final make up of certain groups.
If those countries can do it, why shouldn't Wales be capable of it too?
The Wales players looked physically and mentally shattered in the immediate aftermath of Iran. They knew a nation hadn't waited 64 years for this.
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This is where the manager comes in. It's up to him to rally the troops, get Wales playing with verve, pace, passion, width and creativity again and put the frighteners on England.
Under Gareth Southgate the Three Lions are a conservative bunch. Wales can forget about winning 4-0, of course, the result they need to guarantee progress. Keep it tight at the back, put on the afterburners going forward, try to nick a goal from somewhere - and then hope to learn USA v Iran has gone their way, too.
Yes, we know it's hugely unlikely, but as the old saying goes, football is a funny old game.
Wales, thus far, haven't really fired a shot in anger over 200-plus minutes of World Cup football. As a consequence, everything suddenly hinges on the big one versus England.
Managers have devised game plans for other teams to produce those huge tournament upsets. It would be a crying shame if Wales don't come to the World Cup party and it ends with us bottom of the group, without a win and with only a Gareth Bale penalty to show from three matches.
Sadly, England will probably win. But let's just hope Wales produce a 90-plus minutes of football the fans can be incredibly proud of, which remind us of what the real Wales are about - and which make us hanker for what might have been against USA and Iran.
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