Kershaw had an X-ray and an MRI on Friday, but manager Dave Roberts didn't know the results of the MRI prior to Los Angeles' game against San Diego. Roberts said Kershaw was sore on Friday.
"Hopefully it's going to be shorter than longer," Roberts said.
Roberts said he's hesitant to give a timeline until they have results of the MRI but noted that he expects him to be back in time to make a few starts before the postseason.
Kershaw said he felt discomfort while he was warming up before the bottom of the fifth inning Thursday. The three-time NL Cy Young Award winner winced and pointed to his dugout, and then walked off the field gingerly with an athletic trainer.
"Just felt something kind of lock up there in the fifth and couldn't really throw after that," Kershaw said Thursday. "Something in my back again. ... I saw a doctor, but really nothing to do until -- just see how I wake up in the morning, is probably the first thing, and then go from there."
Kershaw (7-3, 2.64 ERA) has dealt with back issues throughout much of his career. He spent time on the injured list earlier this season due to inflammation in a pelvic joint.
The Dodgers will need to fill Kershaw's spot in the rotation in the near future. Dustin May, who had Tommy John surgery last year, is trending toward a return soon. May has another rehab start Tuesday in Triple-A Oklahoma City.
"The world will look different then,'' Roberts said. "Then we'll make a decision on whether he should make another one, which is most likely, so now you're looking at somebody in our system to make that (next start). (Ryan) Pepiot certainly makes sense.''
Moronta is 0-0 with a 4.67 ERA and 20 strikeouts in 17 1/3 innings. Outman went 6 of 13 with one homer and three RBIs in four games with the Dodgers.
Information from The Associated Press was used in this report.