An MRI revealed that Gasol, the NBA's reigning Defensive Player of the Year, has a Grade 2 sprain of the MCL in his left knee.
Gasol will not undergo surgery, the team announced. The All-Star suffered the injury in the second quarter of Friday's loss to the San Antonio Spurs.
Replays indicated there was little if any contact before Gasol grabbed his knee under the Spurs' basket. He went to the Memphis locker room and did not return.
Gasol was second on the Grizzlies in points, rebounding and assists entering the game.
Information from The Associated Press was used in this report.