Andrew Bogut returned to the injured list on Friday night when he missed Golden State's game against the San Antonio Spurs with what the Warriors termed back spasms.
Bogut will be out indefinitely as the Warriors await MRI results on his back.
"We just don't know," Mark Jackson said. "There's no red flag or anything. We just don't know.
"We realize this is a process. For a guy who has not played in a long time, you're going to go through your body reacting to it. We know how important he is to this basketball team. This is something we didn't expect, but at the same time, we'll take care of it and move forward. I'm very comfortable and confident in what (Andris) Biedrins and also Festus (Ezeli) can do, and what they have done for us."
Bogut was suffering spasms in his mid-back area, according to a Warriors spokesman.
Bogut, who had seven points and 11 rebounds on Wednesday, has missed extended time with back issues in the past.