Scotland face two vital games in the Nations League as they play Israel and Albania in the coming days, but things are already not going in the team's favour.
Celtic's Tierney has left the side after a leg injury he sustained with his club, making him the ninth man to make himself unavailable.
Despite the lack of personnel at McLeish's disposal, the former Aston Villa boss wanted to concentrate on those players who are still in contention.
"We kind of have the nucleus here and that is important." McLeish said.
"We are going to concentrate on the guys who are in the squad and pay them our utmost respect. I really trust them. We have two really big games ahead of us and we can do it.
"The players who are not here, are not in my control.
"What is in my control is these guys in the squad right now who I have the utmost confidence in and we want these boys going into these games believing that they can win and give us a foot into the Euros.
"I do really believe that we have the players at our disposal to cope. There is no doubt about it."