In November 2011, Glasgow took the field against Leinster at the Royal Dublin Showground.

It was the second round of the Heineken Cup's pool stages and Warriors were in optimistic mood.

They had opened the tournament with a win against Bath the previous weekend, while Leinster had needed a last-gasp penalty to scramble a draw with Montpellier. Glasgow's tails were up – with disastrous consequences.

A shattering experience followed as their forwards were blown off the park. Glasgow conceded a try within the first few minutes and coughed up three more before half time on their way to a 38-13 defeat, with Leinster taking their foot off the pedal in the second half.

You could almost smell their scorn for Glasgow's over-confidence and the lessons of that game are both obvious and cautionary on the day Scotland take on Ireland at Murrayfield. And all the more so as Sean O'Brien and Jamie Heaslip, ruinously effective at openside and No 8 for Leinster 15 months ago, will fill the same positions for Ireland today. This afternoon, attention will inevitably be drawn towards Paddy Jackson, Ireland's baby-faced debutant fly-half, but the performances of Heaslip and O'Brien may be a far better barometer of their fortunes.

For the Scots, Dean Ryan is a man who could have just as big an impact. The interim Scotland forwards coach has been widely credited with putting a Saturn V-sized rocket up his pack's collective backside after the England game, and he will be starting the countdown again if he sees any sign of his players slipping back into bad habits.

Ryan has spent too long in the fiercely pragmatic surroundings of English club rugby to have much respect for one-off victories and Scotland, who beat Italy a fortnight ago, have not won two consecutive Six Nations games since 2001.

That was the year the foot-and- mouth crisis interrupted the championship, so there was a six-month gap – and a Lions tour – between the Murrayfield successes over Italy and Ireland, probably just long enough for the players to clear their minds of the idea they had just turned into world beaters.

Ryan told yesterday's eve-of-game briefing: "The challenge to back up [results] week in, week out is our biggest one, mentally as well as everything else. Our history says that we can't back up the week after [a win]. We have to challenge that, we have to do something different."

What he actually means is do something the same. The game plan Scotland rolled out against Italy is pretty much what they will need against Ireland, in terms of its focus on a few basics at least. Ryan and Scott Johnson will demand a few tweaks, a good number of them around the kicking game, but the core importance will remain on squeezing Ireland on the gain line and on matching them in the breakdown battle.

In other words, on keeping Heaslip and O'Brien in check. Scotland also know they cannot rely on Jackson making the kind of hash of things that Luciano Orquera did for Italy a fortnight ago. Even without gifting the interception that led to Stuart Hogg's try, Orquera was probably worth about 10 points to the Scots.

Looking at things realistically is another of Ryan's obsessions. "I am astounded at the rollercoaster that Scotland goes on," he said. "We won one game against Italy and suddenly we are at the dawn of a new era.

"Two games ago we got bumped by England. Three games ago we lost to Tonga. Everybody has a responsibility to understand where this side is. Yes, there is some talent in it. Yes, we are realigning some of the things we think are important in Test match rugby, but we've only won once."

Ryan is enough of a diplomat not to dwell on what went on before his arrival, but it is clear he believes not enough time was spent on fundamentals. It was as if the team were trying to put up the curtains in a house that was only half-built. Preparations now involve no fancy drills, no motivational speakers.

While Ryan concedes Scotland's failure to back up wins may be a kind of mental block, there have been no sports psychologists either. "I don't think it's the right time," he said. "I think you just cloud the issues. That's not to say they haven't been good in the past and they will be used again, but not until we are in the right place.

"Coaching can get clouded, especially if you aren't winning. You are desperately seeking new ideas to prompt something and the whole message can get clouded. The opportunity we have is to strip it back and be very clear that if we can get a few things done well then we stand a chance of winning at inter-national level. It's as simple as that."