Michael O'Neill hopes Jonny Evans will be fit for his first competitive game as Northern Ireland boss and insists the door is open to those missing from his squad.
Manchester United defender Evans brings vital big-game experience to O'Neill's plans and will be a key figure in 2014 World Cup qualification.
He is, however, yet to figure for United this season after undergoing ankle surgery towards the end of the 2012/13 campaign and making a belated return to training.
Evans is in line to marshal the heart of Northern Ireland's back four, though, when they start out on the road to Brazil on 7th September with a trip to Russia.
"Jonny has had his injuries and he had to have surgery but he's made progress with his return and he was on the bench on Saturday," said O'Neill.
"There are 10 days before the Russia game and we hope his fitness can really improve. He is vitally important to us.
"Jonny is very hopeful and optimistic that he will be ready to play.
"I have spoken to Sir Alex (Ferguson) but I also keep in touch with the players directly. The communication between myself, the players and the association is very good and we'll contact them if there are any issues with their fitness."
While Evans could be involved in a double-header against Russia and Luxembourg, David Healy, Grant McCann and Sammy Clingan are among the senior figures to have missed the cut.
O'Neill has, however, made it clear that all three could be drafted back in as he does not have lavish resources available to him.
He said: "It's not as though I'm picking from 100 players, so those who are not in the squad can still be important for us.
"Sammy's club situation is not resolved and he is without a club, David Healy was too and he has just signed with Bury.
"David has had 60 minutes of competitive football this season and that is not enough to quite make this squad, but I've spoken to him and he's in my thoughts for future games.
"Grant has not started the initial games for Peterborough but he is on standby for the squad.
"The door isn't closed on them, in fact it's not closed on anyone who is eligible for Northern Ireland."