Fultz will be re-evaluated Tuesday.
The news comes after Fultz's agent, Raymond Brothers, told ESPN.com's Adrian Wojnarowski on Tuesday that his client received a cortisone shot to alleviate pain and inflammation in his shoulder.
Brothers also disclosed Fultz "literally cannot raise up his arms to shoot the basketball," which explained why he was struggling with his form at the free-throw line.
"He decided to try and fight through the pain to help the team," Brothers said. "He has a great attitude. We are committed to finding a solution to get Markelle back to 100 percent."
"As I said to Markelle, this is not going to define you," head coach Brett Brown told reporters. "This first season is not going to define you. We are going to focus on all the other things that will define you."
Jerryd Bayless and T.J. McConnell will likely see extended minutes with Fultz out of the lineup.