A minefield in midfield
Loss of key men leaves O’Neill stuck in the middle but Wes and McGeady can step up
It was all very simple for Mick McCarthy when he tried to get his team to the World Cup finals.
For your midfield four in that 2002 qualifying campaign - and it was always a midfield four - you play Kevin Kilbane on the left, use one of your other wingers on the right (Jason McAteer, Gary Kelly, Mark Kennedy or Damien Duff) and then pick either Mark Kinsella or Matt Holland for the role of Roy Keane's sidekick in the centre.
A simple formula, helped by good attendance records (Kilbane was an ever-present and Keane missed just two group games), quality at your disposal (all of those options were Premier League players) and their vast experience at international level.
If only things were that clearcut for Martin O'Neill this week.
Suspensions for Robbie Brady and James McClean and an injury to Jon Walters leaves the Ireland boss short on options and experience when he picks his midfield to face Moldova.
Well, he has options, with 12 available midfielders crammed into his squad.
But look closer and you see players among that midfield dozen who are not match-fit (James McCarthy), have been unconvincing when asked questions on the international stage of late (Harry Arter), are heading into old age (Wes Hoolahan will be 36 the next time he has a birthday) and lack experience at competitive international level (Eunan O'Kane and Conor Hourihane have, between them, played 15 minutes in competitive matches).
His goalkeeper (Randolph) and back four (Christie, Clark Duffy, Ward) are set in stone, while barring a shock debut (Scott Hogan) or recall (Daryl Murphy), Shane Long will start as a lone striker.
So, what he does over the next two days, and how he negotiates that minefield in midfield, could well define O'Neill's time as Ireland manager.
Does he assume that winning at home to Moldova - they are officially the sixth-worst national team in Europe and once they are outside of Chisunau are unable to keep a clean sheet- is a given so he can pick a side with a view to keeping men fresh for the bigger test to come in Cardiff?
Keep Wes Hoolahan on the shelf, ready for export to Wales on Monday night and a central role? Trust Harry Arter to be the talent he has been in the Premier League for his club and not the pale imitation we saw in Tbilisi last month, when he was hauled ashore after a very poor 60 minutes?
Give Glenn Whelan one last outing in what will probably be his last game of international football in Dublin (should Ireland fail to reach the playoffs)?
Of the not-so-dirty dozen midfielders, McCarthy will not be risked while Daryl Horgan and Jonny Hayes might not even make the bench.
O'Neill has spoken highly of Eunan O'Kane and his form for a Leeds side who were, until recently, top of the Championship, and Conor Hourihane is also a player admired by the management team, a player with an eye for goal (he has scored more league goals this season than Shane Long, Scott Hogan, Sean Maguire and Aiden O'Brien combined).
O'Neill could set aside the system he's used for long spells and play two strikers, an all-Munster partnership of Shane Long and Daryl Murphy, and he could also pull off a surprise and pitch the uncapped Hogan in from the start.
But it's likely that he will pick five in midfield. David Meyler is almost certain to start, his loyalty over the years being repaid with a rare starting role in midfield, while Harry Arter might get the nod ahead of Whelan to play alongside Meyler as part of a two-man formation in front of the back four.
In front of them, only Jeff Hendrick is guaranteed to start as the older statesmen in the squad, Aiden McGeady and Hoolahan, hope that past service in the national interest will serve them well so they get to start.
O'Neill has pulled off one surprise in his selections in this group, Kevin Long selected ahead of more experienced defenders for the home game with Austria, and he didn't disappoint.
Hourihane lacks that experience but he could emerge from the fringes, a challenge from O'Neill and Keane to see if he can deliver, having (by Hourihane's own admission) struggled on his debut against Iceland last March.
A midfield five of Meyler and Arter, fronted by McGeady, Hoolahan and Hendrick, could offer O'Neill the experience and nous to get the Moldovan mission done. But it won't be easy.