The incident happened inside the opening stages at the Camp Nou, when Messi cut inside from the right wing, and his left footed shot was blocked by visiting defender Pablo Bigas.
Messi received treatment to his left knee on the pitch, then tried to continue for a few minutes, but soon admitted he could not continue and was replaced by youngster Munir El-Haddadi with just 10 minutes played.
Messi was quickly taken to the nearby Creu Blanca hospital for tests on the injured joint.
Barcelona posted a tweet confirming Messi’s injury and said that he has a tear in the internal collateral ligament of his left knee and will be out for around 7-8 weeks.
Messi has a tear in the internal collateral ligament of his left knee. He will be out for around 7-8 weeks pic.twitter.com/TLor97gmou