Williams said Pinson would need an MRI to assess the extent of the injury, which occurred early in the first half. He had no idea when Pinson might return.
Pinson, a key catalyst for the Tar Heels at multiple positions, went into Tuesday's game averaging 9.5 points, 6.0 rebounds and 4.4 assists per game this season. He also has connected on 81 percent of his free throws.
North Carolina have now dropped three games in a row. The Tar Heels were down by double digits against the Tigers entering the second half.
Pinson's injury and the loss capped a turbulent day for Williams' squad. Reserve guard Jalek Felton has been suspended by the team and cannot participate in any university activities, the team announced on Tuesday. The team said it could not provide any details due to federal privacy laws.
The Associated Press contributed to this report.
Pinson heads to UNC locker room after awkward fall
Theo Pinson goes up for a rebound but lands awkwardly on the court and needs assistance to the bench. Pinson would head to the locker room.