The 7-foot-3 center from UConn was injured late in the first quarter during a battle under the Memphis basket. Replays appeared to show Thabeet's jaw colliding with forward Zach Randolph's head.
Thabeet had just entered the game a minute earlier.
Thabeet was playing in his seventh game of the season. He had scored four points and grabbed 11 rebounds in his previous six games, and also recorded six blocks.