An inflammation was discovered during an MRI Thursday. Gasol returned to action a week ago after missing eight games with sore knees.
The Lakers said Gasol would be listed as probable for Friday's game against Portland.
Gasol has played in at least 29 minutes during each of his four games since returning from the knee problems. He scored 19 points and grabbed six rebounds in 37 minutes during the Lakers' loss to Denver on Wednesday.
He is averaging 12.6 points during his 21 games this season. Gasol is in his 12th NBA season and has never averaged less than 17 points for a full campaign.