"I'm not going to speculate on how many games or how much time he's going to be out right now," Lakers coach Byron Scott said. "But just talking to our trainer, it didn't look good. We'll just have to wait and see and hope for the best."
The Lakers also said rookie forward Julius Randle, who is already sidelined for the season after suffering a broken right leg in his NBA debut, will undergo surgery this week to fix an issue dating back to high school that reportedly led to him falling in the 2014 NBA draft.
The 6-foot-7 Johnson, a former fourth overall pick out of Syracuse in 2010, went scoreless in 12 minutes against the Pacers and is scheduled to have an MRI in Los Angeles on Monday.
Johnson, now in his fifth NBA season, entered Monday averaging 9.7 points and 3.8 rebounds.
Randle will have right foot surgery Tuesday morning to replace the screw in the fifth metatarsal, which he broke during his senior season in high school.