Ikechi Anya has been ruled out of Scotland's crucial Euro 2016 qualifier with Poland due to a calf problem.
Gordon Strachan's side need maximum points from the clash on Thursday if they are to keep alive their slim hopes of reaching the finals in France next year.
However, both Anya and Charlie Mulgrew have been confirmed as unavailable by Strachan, leaving the coach with a selection headache for the visit of Adam Nawalka's side.
"Ikechi is not going to make it, he has a tight calf so he has gone back to get treatment at Watford," he said.
"James Morrison (suspended for the Poland game) is going to struggle [to feature against Gibraltar]. He got an injury at the end of the game against Crystal Palace the other day.
"Charlie Mulgrew was never going to be fit. Charlie is only here because he wanted to be here and add to the squad and what we do behind the scenes and he has certainly done that.
"Each of our strikers have different assets and pluses but we don't have an all-round guy who has every one of these and then you have to think what type of game should it be, and pick the players that would suit that game.
"In saying that, we have decisions to make in midfield where we have good players although it does diminish a bit in wide positions with Ikechi leaving. So we will try to envisage the game and think what is the best XI for that game."
Strachan later stressed he is confident in his defence's ability to keep in-form Robert Lewandowski quiet, despite the Bayern Munich star having scored 12 times in just four appearances.
"Most of our work has been done in group defending and group attacking and hopefully our group defending will nullify any areas that their top players want to play in.
"But the secret is actually, if you keep the ball long enough and longer than them, then the chances of them scoring a goal is reduced. So that is what we have to try and do. And if we have more chances and more goals then that will be fine. But we understand that there are some right good players in the Polish side."
