It is the striking department that is causing Colin the most concern with three of his regular strikers unavailable to him. Lee Barnard is still struggling with a hand injury, while Jamie Slabber and Michael Malcolm are required for FA Youth Cup duty at Crystal Palace on Thursday evening.
It is a factor that will also deny Colin the services of midfielder Mark Yeates. Jonathan Blondel (shoulder) and Paul O'Donoghue (knee) are still out.
"With the week shaping up the way it is, the boys who might have come up and had a game won't because of the Youth Cup," explained Colin.
"It won't be a mix and match team, but it will be a side where the balance probably won't be exactly as you would expect.
"We're going to have to look at it and see who we've got and what type of formation we can play.
"It is unfortunate timing, Jamie Slabber would have had a run of games before now, but he got injured, the same with Lee Barnard. Michael Malcolm played last week but has now got the Youth Cup. Someone will play there, it could be a case of improvising."
As with all situations of this type, Colin points out that it provides opportunities for others that must be seized.
"It is an opportunity, looking at the appearances, one or two haven't had as many in the reserves as we would have liked and hopefully this will give them a chance.
"Whatever position they play, they must show something within the game that shows us they deserve another go."
Colin Calderwood is fast learning the perils of football management as he ponders selection dilemmas ahead of the reserve clash with Coventry City at Stevenage tonight, kick-off 7pm.