Republic of Ireland manager Giovanni Trapattoni is keen to find out from Robbie Keane and Richard Dunne whether they are still committed to the team.
Just 48 hours ago Trapattoni expressed confidence that his most senior players would return to the fold for the start of the World Cup qualifiers next month.
Shay Given has since announced his retirement from international football, and Trapattoni hopes the likes of Keane and Dunne do not follow suit.
Neither man will be involved in Wednesday's friendly against Serbia but Trapattoni still considers them key players going forward.
Dunne's immediate concern, though, is recovering from a groin operation that will keep him out until the middle of next month at the earliest.
Trapattoni said: "Richard sent me a message recently saying he would not be ready for the game with Kazakhstan because he needs a few weeks to recover from his injury, that the game was too soon.
"I answered him and said after this friendly, after he has recovered from his injury, we would review the situation, but I've told him we need him, it's true. He will let us know.
"As for Robbie, I've also sent him a text, but he's not answered me. I've checked my mobile.
"I will speak with him before I announce my next squad (in around 10 days' time for the Kazakhstan game).
"He needs to tell me whether he wants to come back or what he wants to do.
"We can decide after this game because it's important for us to look at the other players. We have (Shane) Long, (Simon) Cox and (Jon) Walters.
"After this game, and before the one with Kazakhstan, we can think about this situation."
It means the game with Serbia is now more than just a pre-season friendly as it could form the foundation for future squads.
In naming his side, Kieren Westwood now has to fill Given's shoes in being named number one, with Paul McShane, Darren O'Dea, John O'Shea - also wearing the captain's armband - and Stephen Kelly lining up in defence.
Aiden McGeady, James McCarthy, Glenn Whelan and James McClean will form the midfield, with Walters and Long in attack.
"This friendly match is a good opportunity to see some of the new players, to give them a chance to prove they can be part of the national team," added Trapattoni.
"I'm not expecting a great result or a beautiful match because we all know the players are at the start of their season with their clubs.
"But if we can get a good result, that brings confidence and builds the trust within the team.
"When you have young, new players their morale goes down after a defeat, so a good result would give us that confidence and trust."