Boss Joe Schmidt says selecting Ireland's World Cup squad will involve the "most difficult decisions" of his career as he prepares to announce his 31 names for the tournament.
Schmidt must give his squad to World Cup organisers on Monday, although it won't be made public until Tuesday.
The wing and full-back options may have caused Schmidt sleepless nights.
And there is speculation Andrew Trimble may be in a battle with Dave Kearney for one of the wing spots.
The duo were Ireland's first-choice wings as recently as the victorious 2014 Six Nations campaign but both missed most of last season's action through injury as Tommy Bowe, Simon Zebo and Luke Fitzgerald filled the wing berths.
Missing out on the World Cup would be a devastating blow for Trimble, who was named Ireland's player of the year after the 2013-14 season, but then suffered a serious toe injury.
Schmidt's tough back-five decisions
With Keith Earls also again part of the back-five equation and, like Fitzgerald, capable of operating at centre, Schmidt has wing riches that he is unlikely to be able to accommodate.
That have even been suggestions that British and Irish Lions star Bowe could be under some pressure, but the Monaghan man's omission would be startling.
The rumour mill would also have one believe that Schmidt may consider giving himself some selection leeway by opting to take only two scrum-halves in Conor Murray and Eoin Reddan, with fly-half certainty Ian Madigan having occasionally operated at number nine for Leinster.
However, this would appear the kind of gamble not normally associated with the meticulous Ireland coach so either Isaac Boss or Connacht youngster Kieran Marmion is likely to be included as third scrum-half.
With regular full-back Rob Kearney nailed on, the other back-five issue is whether Schmidt opts for Felix Jones or Simon Zebo, with the latter's mercurial talents possibly proving too much for even the hard-nosed New Zealander to overlook.
If Earls and Fitzgerald are selected, Ulster's Darren Cave will probably lose out in the centre equation with Robbie Henshaw and Jared Payne certain to travel after forming an effective Six Nations partnership last spring.
Of the other backs, fly-half Johnny Sexton will have Madigan and Paddy Jackson as his back-up personnel barring a major surprise.
Healy likely to be part of Ireland's pack picks
In terms of the forwards, Schmidt came as close as he possibly could last Thursday to admitting that loose-head prop Cian Healy will be in the 31 despite his injury woes over the past 12 months.
World-class operator Healy missed the early part of last season because of a hamstring injury and while he featured in the Six Nations, was then forced to undergo neck surgery in May.
However, according to Schmidt, the prop's recovery from his most recent operation has gained real momentum over the last week and that suggests impending good news for the Leinster front rower.
Also in the front-row permutations, Marty Moore's injury problems have come at precisely the wrong time for him but Nathan White looks well placed to edge out the versatile Michael Bent after performing creditably in Saturday's defeat by Wales.
Dave Kilcoyne also appears in line for a prop berth alongside certainties Mike Ross and Jack McGrath with Rory Best, Sean Cronin and Richardt Strauss the obvious hooker options.
Skipper Paul O'Connell, Devin Toner, Donnacha Ryan and in-form Iain Henderson look guaranteed second-row selections which is likely to mean disappointment for Dan Tuohy.
And while Schmidt has been impressed by youngster Jack Conan's efforts in recent weeks, it will be a surprise if Chris Henry and Jordi Murphy don't join regular starters Peter O'Mahony, Sean O'Brien and Jamie Heaslip as the back-row picks.