The injury could knock the key reserve for the NBA champion Spurs out of the upcoming World Cup of Basketball, where he was scheduled to play for Argentina.
The tournament starts at the end of August in Spain. Ginobili wrote Tuesday on his Facebook page that his availability will depend on how he feels in about three weeks, but that he remains optimistic.
It's unclear when Ginobili was injured. He averaged 14.4 points in the NBA Finals, when the Spurs beat Miami in five games to give Ginobili his fourth championship.