Vucinic came off the bench to inspire Juve's triumph.
Carrera said: "It's hardly news that Vucinic is a great player, but he was tired after international duty and Alessandro Matri was in better shape.
"Vucinic knows he is an important player, but he has to prove he deserves his place in training, just like everyone else. If someone thinks they are untouchable then they might relax during training. This way we keep everyone on their toes."