Sullinger suffered a bone bruise taking a charge from Orlando's Maurice Harkless in the second quarter of Monday's win against the Magic. He sat out practice Tuesday while getting an MRI. Sullinger warmed up before Wednesday's game, but is not at full strength.
"It's still day to day. We didn't even know officially [Sullinger would be out] until five minutes ago," Celtics coach Brad Stevens said while addressing reporters 95 minutes before tip-off. "He's got the bruised knee [and] obviously isn't feeling 100 percent running and jumping off it. It's a great opportunity for somebody else to step up."
Stevens said Kris Humphries will fill Sullinger's minutes. Humphries has played well in small bursts this season, including while filling in for Sullinger on opening night when the second-year player was suspended for the first game of the year in Toronto.
Sullinger has averaged 11.3 points and 5.1 rebounds in seven games this season.