A Cal spokesman said Wednesday night only that Wallace injured the hand and was being evaluated, and that more information would be available Thursday.
No. 4-seeded Cal opens tournament play against Hawaii on Friday.
Wallace previously suffered a fracture in his right hand during a January practice and missed five games.
A 6-foot-5 senior, Wallace leads the team in scoring (15.3 points per game), assists (4.4), steals (1.0) and minutes (32.2). He also is averaging 5.4 rebounds per game.
Wallace is coming off one of his best games of the season, having scored 26 points in a loss to Utah in the Pac-12 semifinals last week.
Wallace’s injury comes on the heels of the firing of assistant coach Yann Hufnagel after the university found that sexual harassment allegations against him were substantiated. In addition, UC Berkeley officials are reviewing whether head coach Cuonzo Martin correctly handled the allegations against Hufnagel.
The Associated Press contributed to this report.