Adam among Scotland injury doubts
All three were involved in the 3-1 win over Wales, with Morrison on the scoresheet, but Adam is struggling with back and groin problems, Caldwell has a hip injury and Morrison has a calf strain.
Stephen Crainey, as expected, has returned home to undergo an operation.
Levein said: "We have a few problems. Gary Caldwell and Charlie look unlikely to play. There is also a little concern over James Morrison.
"It's like any other game, I will wait and get an indication from our medical team just exactly who is going to be available and select the players from there.
"The good thing for me is that we have a particularly strong group with us and if I should miss a few players I should have able replacements.
"Of the players who are injured just now, I would say Gary Caldwell is the least likely to play."
Scotland will battle the Republic for the silverware in the tournament's final game.
Levein added: "We don't want to lose anybody. We don't want to lose Gary Caldwell, he is a very influential player and a great leader and a great example to others in the team.
"We don't want to lose Charlie. James Morrison's form has been scintillating for us any time he has played so we don't want to lose him either. It's just the nature of the game. If we lose players, we lose players and we have people capable of taking their place."
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