Gasol, 29, was injured during Wednesday's loss to the Houston Rockets. He is averaging a career-high 19.4 points, 8.0 rebounds, 3.6 assists and 1.5 blocks for the Grizzlies.
He was limited to 59 games last season after spraining the MCL in left knee in November 2013. He returned in January and led the Grizzlies to the playoffs, where they lost to the Oklahoma City Thunder in a seven-game series.
Gasol is in the final season of a four-year, $57 million contract.
The Grizzlies have started the season 15-3, second to only the Golden State Warriors. They are allowing just 93.1 points per game, which is second behind the Houston Rockets.
They host the Spurs on Friday night.
- Paul Palladino