Kershaw 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 a trainer.
"Just felt something kind of lock up there in the fifth and couldn't really throw after that," Kershaw said. "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."
The 34-year-old Kershaw made 66 pitches through four innings, allowing one earned run and three hits with four strikeouts. He left with a 4-2 lead and the Dodgers went on to beat the Giants 5-3 to complete a four-game sweep.
"Obviously, anytime a pitcher's got to come out of a game, there's some concern level," Dodgers manager Dave Roberts said. "Given it's his back which has been problematic at times -- we just won't know more until we get some tests."
Kershaw 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.
Kershaw was 7-3 with a 2.66 ERA in 14 starts coming into the day.