Gasol, who missed the first two months with a sprained MCL, appeared to aggravate it in the third quarter against the Magic.
On the play, Gasol banged his knee setting a screen and immediately exited the game, limping off the floor.
The Grizzlies, who struggled without Gasol, went 13-3 in January since he returned to the lineup. They've steadied out a bit lately, but obviously losing him for an extended time would be catastrophic.
Th Grizzlies went on to win, 86-81, improving to 29-23.