Carter played 25 minutes during Boston's preseason opener against Cleveland on Thursday, but the third-year pro is under the weather and not be available for Saturday's contest. His next chance to play is Wednesday against Charlotte.
Garza took an inadvertent elbow to the nose from teammate Chris Cenac, and the former was taken to the locker room shortly thereafter. Assuming Garza doesn't return, he'll end his night with eight points (4-9 FG), seven rebounds and one assist over 11 minutes.
Harper is working through right shoulder illness, which has prevented him from playing in each of the Celtics' first two preseason games. His next opportunity to play is Wednesday against the Hornets.
