The Spurs say Ginobili had an MRI on Monday after getting hurt in the second quarter of Sunday night's game against Minnesota.
Ginobili didn't play after halftime against the Timberwolves after scoring 12 points. He also had five assists in his 12 minutes. San Antonio won 106-88 for its 12th consecutive home victory.
The 35-year-old Ginobili has already dealt with back spasms, a left quadriceps bruise and a thigh bruise this season, his 11th in the NBA. In 36 games, he is averaging 12.9 points and 4.6 assists per game.