The moment of truth has finally arrived for England's players and management. Their three-week stay in the South Island may have had its bizarrely eventful moments but the sharp end of this Rugby World Cup has mostly been somewhere over the rainbow. Not any longer. The dwarves and the bungee-jumping are about to be replaced by something altogether bigger and scarier.

It is still possible, after Argentina's dramatic win against Scotland in Wellington, for the bottom to fall out of England's world. Should Martin Johnson's side contrive to lose badly to Scotland this Saturday and book themselves on the night train to the big adios, a huge amount of time and effort will have been wasted. Finish top of Pool B and they may yet be hunting a genuine pot of gold at Eden Park next month. Mentally, either way, the knock-out stages have effectively started a week early.

Hence the rising sense of anticipation now the squad has relocated up to Auckland. The relative peace and quiet of Dunedin, with its strong Scottish links, has been a pleasant bonus for the English, who resided on Princes Street and trained beside the junction of Burns and Murrayfield Streets. Now the scenery and dramatic focus have shifted. Essentially, a new Six Nations campaign is about to commence, the only difference being the introduction of a sudden-death element.

That, at least, is how England will be tempted to view it. Beat Scotland and a fractious France await in the last eight. Leap that unpredictable hurdle and either Wales or Ireland should loom in the semi-finals. Given England won a Six Nations title barely six months ago, they are entitled to feel they can do something similar again. Had they beaten Ireland in Dublin and clinched a grand slam, they would be more confident still.

But they didn't, and departure lounges are full of teams that forget knock-out rugby is a very different scenario. England generally react well to do-or-die propositions but 10 of their starting XV in the free-scoring demolition of Romania are experiencing their first World Cup. "Everything is magnified at a World Cup," said Johnson, as impressed as anyone else at the way the All Blacks sliced up French pretensions on Saturday. "It's all about handling the pressure. We need to make a mental switch … we've played three games but it's not really started yet."

He scarcely needed to add that the former England coach Andy Robinson has been plotting ways of ambushing England for months and months. If ever there was a man with a considerable point to prove, it is Robinson this Saturday. "Know your enemy" is the motto of the best generals and no one knows England better. Johnson and his lieutenants will be wary of sleepwalking into a tactical trap, as the defence coach Mike Ford acknowledges. "I know Robbo will put a new play in that I've not seen … he's the type of coach that's very good at that. I expect them to throw something different in for us."

England, therefore, need to get their heads together and think clearly. Do they simply take the Scots on up front and risk getting dragged into a slow-ball slugfest, or do they aspire to play at a pace that brings their dangerous back three into play and stretches Graham Steadman's well-organised Scottish rearguard? When England have struggled at Murrayfield in recent times it has nearly always been because they have underestimated Scotland's effectiveness at the breakdowns and failed to establish any kind of tempo.

Partly for that reason, Johnson's initial preference for Jonny Wilkinson as his starting No10 may need reassessing. Wilkinson was instrumental in setting up the best of his side's 10 tries against the Romanians, his deft inside ball releasing Manu Tuilagi for a cannonball run to the line. For all his many accomplishments, though, he has not been a reliable hammer of the Scots.

After the Calcutta Cup games of 2008 and 2010, neither of which England won, he was dropped for the next game on each occasion. Toby Flood, by contrast, was at No10 for the Six Nations games of 2009 and 2011, both of which England won. There is a case, with Ben Youngs surging back to form, for reverting to Flood and using Wilkinson off the bench as last-quarter insurance.

If Johnson opts to stick with the status quo, it will tell Robinson plenty. The Scots will also feel their task will be considerably simplified if they can keep the ball away from England's back three. Mark Cueto, Chris Ashton and Ben Foden work well as a unit and accounted for seven of England's tries, with the fit-again Cueto and Ashton registering three apiece. As Ashton admits, it has done the pair's confidence no harm at all. "It does take a few weeks to get back into it, even though you deny it. I do feel I'm back on song again."

Tuilagi also has an increasing hint of x-factor about him, and England's defensive system has coughed up just one try in three games, with 17 scored at the other end. They are happy to back their fitness against all-comers, have fewer injury issues than some of their rivals and have enjoyed a favourable draw. Three more wins and suddenly they will be in a third successive World Cup final. If that does not concentrate minds, nothing will.

Kitson's England team to play Scotland

B Foden; C Ashton, M Tuilagi, M Tindall, M Cueto; T Flood, B Youngs; A Corbisiero or M Stevens (fitness permitting), S Thompson, D Cole, L Deacon, C Lawes, T Croft, L Moody (capt), J Haskell.