MARTIN O'Neill has confirmed that James McCarthy's latest scan on his fatigued hamstring came up clear and that he was ruled out of tonight's action in Glasgow because he wasn't able to train.
"James, realistically was always an outside chance. He has improved immensely and he went for another scan which was quite clear and is good news," said O'Neill.
"But it is a muscle injury and he needed to do something today to see what risk he had. Better not to risk him," he added.
Glenn Whelan's decision to withdraw came after a trojan effort to get himself fit in time. "Glenn hurt himself in Germany but hadn't done much training but was hopeful himself. But just yesterday, he didn't feel he had done enough work to be chosen for the team.
"Naturally, I've been been thinking about it for some time anyway and there was always the possibility they would not be ready.
"I got a call late on to tell me Glenn might be coming when I had probably ruled out anyway.
"James felt it (hamstring) on Sunday and really we have been working on the assumption that they might not make it."
Likely replacement Darron Gibson hasn't had much football either and when asked whether he will be up to the task for such an intense game, O'Neill didn't mince his words.
"If chosen, he will have to be up for it. We can't do anything about that and that will always be the case with us where have one or two important players for us who will not play much at club level."
The Ireland boss is reacquainting himself with old haunts around Parkhead although one room will remain a mystery to him until kick-off time. The away dressing-room.
"I must admit it will be strange to walk into the club and turn right rather than left to go to the away dressing room. I'm not sure ever set foot in away dressing-room," said the former Celtic boss.