BY this stage of Martin O'Neill's tenure, we know that there will be a guarded response when he is pressed on the finer points of team selection.
he Ireland manager prefers to keep his players guessing so he is not suddenly going to make public pronouncements about his private intentions.
This week, however, the well-being of James McCarthy and Glenn Whelan has complicated the Derryman's thought process. It's added a hint of guesswork to his own ruminations over his starting line-up.
In an ideal world, O'Neill would like to be able to field his original first-choice midfielders in the titanic showdown with Scotland.
But with doubts existing over their well-being, he pragmatically accepted that he can't really plan for a scenario which involves both of them starting in Glasgow.
That could have disastrous implications if it wastes his substitute options early in an intensive affair.
And this campaign has already illustrated the value of having a few late cards to play.
So, in the short term, he has to take on board the feedback of his medical staff and reach a consensus on whether either of the players are ready to take part. And if the news is good, he will ultimately have to decide between them.
It would appear that McCarthy, the man of the moment because of his background, has the best chance at this juncture.
He comes into this gathering after a week where he was hailed for an outstanding Europa League performance against Lille and also lasted the duration of a Premier League draw at Sunderland.
Whelan, on the other hand, has not played any football since he sustained an injury in the draw with Germany in Gelsenkirchen.
A strong training session at Stoke HQ on Monday put him in the mix for this big date and his determination is admirable. Yet O'Neill conceded that a lack of match sharpness would be a natural concern.
"Stoke are happy in terms of the injury. It's just what he is capable of doing now," he stressed. "It's fitness. Remember, he has hardly done a thing since the game against Germany.
"The physiotherapist at Stoke has spoken to Alan [Byrne], our doctor. They've been in constant touch really and Glenn was doing well at one stage. I think then he felt that maybe 10 days ago, the chances weren't great. Then a couple of days later, he was feeling much better.
"I think Stoke are happy because the training he is going to be doing for the next couple of days with us, he would have been doing anyway with Stoke.
"When you are coming out of an injury, you are trying to test it all the time. So you just have to be slightly careful.
"But we've got a couple more days and each day [testing it more]... That's the way he wants to play it and that's the way we are doing it. So we'll see how he is by the time we finish on Thursday."
Whelan was on the training ground for the first outing of the week in Malahide whereas McCarthy was in the gym with Stephen Ward but the players who were involved with the clubs over the weekend weren't pushed to the limit.
Ward has an ankle problem and rested it as a precaution and O'Neill is sure he will be ready to start at left-back.
Robbie Keane, who complained of a bad back and hamstring last weekend in Los Angeles, also took it easy in a small game of keep-ball with a smaller group but it would take a catastrophic injury to prevent the skipper from declaring himself unavailable for selection.
With McCarthy, the situation is slightly more complex because Everton are very worried about over-exertion. The promising news is that no scan was required upon his arrival.
"James wants to play," asserted O'Neill. "He wants to play if he's fit and that's very encouraging. He always did want to come and it's great to see him here because he's an important part of the team.
"It's only 48 hours since he had a strain so we'll see how he is. Everton are also involved heavily in the Europa League and he has played a lot of games and I think, as I said, it's one of those situations where you really would have to wait until the last minute."
The other members of the equation are Darron Gibson, Stephen Quinn and Jeff Hendrick with the latter certainly making a compelling case for a bigger role as O'Neill acknowledged.
"Absolutely. Jeff has done very, very well indeed. He had not played much football when the Gibraltar game arrived because of his shoulder injury.
"He has been flying there at Derby in recent weeks and has got fitter which is good news, good news for us and good news for himself."
O'Neill was in decent form at the start of an important week, laughing off his latest comments about his assistant Roy Keane and Alex Ferguson which had dominated the morning papers.
Visitors from Scotland were keen to probe the 62-year-old on the role he played in encouraging Steven Fletcher out of international exile when he was boss of Sunderland and whether he regretted it this week. "All the time, all the time," he smiled.
Still, O'Neill seemed pretty happy with his new striking acquisition, David McGoldrick, who stretched his legs with the group for the first time and has made a positive impression.
Scotland manager Gordon Strachan wanted to bring McGoldrick into his fold and will be disappointed if the Ipswich attacker becomes a hit in the green jersey. Certainly, there is a growing contingent who believe that will be the case and there was a twinkle in O'Neill's eye as he mused on the 26-year-old's talents.
"He can play, he can genuinely play," he stressed. "Let's have a wee look at him. I don't think you will be disappointed. I think he will be a really good acquisition for us during the course of time."
His club colleague Daryl Murphy says that McGoldrick has similar attributes to the absent Wes Hoolahan even though he is known as a striker.
"Yes, very much so," agreed O'Neill, "He can actually play up at centre- forward and really he can come off players and link in.
"That's really the main part of his game, he's very, very good at it. You will be pleasantly surprised over the course of the next year."
Would he be afraid to pitch him in this Friday?
"I don't think I would be to tell you the truth," he responded, "I don't think I would."
The player said last night that he did not arrive for this gathering with great expectations.
"I've not got high hopes for anything," said McGoldrick. "I've not come here thinking, 'I want to do this, I want to do that.'
"I knew how big this game was before I got called up, to face Scotland in a qualifier. It's a big game with a great atmosphere and to be part of it, hopefully, just to be around it, will be a great experience.
"For me, watching how the boys get on, how the manager and the staff conduct themselves, it's a great experience obviously."
Still, the withdrawal of Kevin Doyle last night does reduce O'Neill's striking options although he already has to figure out if he wants a second attacker for this fixture.
The hard-working Jon Walters should have a role to play following his exploits in Gelsenkirchen and Shane Long is knocking on the door after his weekend brace for Southampton.
Springing McGoldrick off the bench at some juncture would be the ultimate wildcard and it is more plausible that he will debut against the United States next Tuesday.
For Celtic Park, it is the search for midfield energy which leaves O'Neill weighing up the merits of taking a gamble.