Dewayne Dedmon has a stress injury in his right foot and is expected to miss four to six weeks.
Dedmon is a sophomore transfer on USC and a candidate for the NBA Draft.
At first, the injury, which was revealed by an MRI on Monday, was deemed a stress fracture.
But team athletic trainer David Borchardt amended that to note that it is a "stress injury" and that Dedmon will be immobilized for one week.
Dedmon suffered a fractured right hand during the preseason.
"I just look at it like, I'll be back," Dedmon said Tuesday. "It's not like it's at the end of the season where I can't finish out the season, but I can hopefully be back before conference."
"It affects us greatly," Kevin O'Neill said. "You can't replace 7-foot, 250 pounds, especially in the situation when we have so many inexperienced guys."