SAN FRANCISCO — Clayton Kershaw knew right away that something was wrong.
Before the start of the bottom of the fifth inning Thursday afternoon at Oracle Park, Kershaw was throwing warm-up pitches when he said he "felt something kind of lock up" in his lower back.
It was an immediate red flag for a left-hander with a history of back problems, including a month-long absence earlier this season because of SI joint inflammation that caused lower back pain.
Kershaw tried to throw another warm-up pitch, but was clearly still in discomfort.
He motioned for a trainer, uttered "It's my back" as he walked off the mound, then made his way slowly to the dugout, appearing to grimace as he disappeared down the tunnel to the clubhouse.
The Dodgers still went on to beat the San Francisco Giants, 5-3, on Thursday, completing their first four-game sweep in San Francisco since 1977 to finish 7-1 on a two-city trip.
But Kershaw's injury — which the team described as low back pain — overshadowed it all, dealing an already banged-up pitching staff another potential blow to one of its most important starters.
"Hard to tell right now," Kershaw said of his injury. "We'll see more tomorrow. Just more back stuff."
How frustrated was the 34-year-old veteran?
"A fair amount," he said with a sigh.
Kershaw's back has been troublesome for years, leading to injured list stints in 2016, 2017, 2018 and 2020.
It was back pain following a cross-country flight in May that triggered Kershaw's month-long injured list stint earlier this season.
Manager Dave Roberts said Kershaw will get "a slew of tests" Friday in Los Angeles.
While Roberts wasn't sure of the severity of this injury, or whether Kershaw will have to go on the injured list, he acknowledged there was some concern "given it's his back, which has been problematic at times."
"We just won't know more until we get some tests," Roberts added.
Kershaw's early exit — which followed four strong innings in which he'd given up his only two runs (one of which was unearned) on a two-run home run to J.D. Davis in the second inning — also came two days after a trade deadline that saw the Dodgers (72-33) stay relatively quiet.
With inflated prices for many stars, especially top-of-the-market starting pitchers, the team gave up its pursuit of several potential trade targets.
Instead, they made only one pitching addition in middle reliever Chris Martin. And they banked on their hope that, as other injured pitchers such as Walker Buehler, Dustin May and Blake Treinen get healthy down the stretch, their staff would solidify itself as a championship-caliber collection.
Any long-term absence to Kershaw would put a major kink in those plans, with the start of the playoffs a little more than two months away.
"Certainly the calendar is not on our side," Roberts said. "But we'll see after tomorrow, after the results, the tests, and also see how he feels."
Added Kershaw: "Hopefully, I don't wake up too bad."
Kershaw's back wasn't the only thing to flare up Thursday.
With the Dodgers leading 4-2 in the bottom of the sixth inning, Giants reliever Jarlín García twice mimicked the Dodgers' head-tap celebration — in which their hitters tap their helmet with a closed fist after getting a hit.
García first did it after striking out Cody Bellinger. When James Outman was rung up for the third out in the next at-bat, García not only did it again, but also pointed at Mookie Betts in the on-deck circle.
Betts said postgame he hadn't said anything to García during the at-bat, but started walking toward the pitcher after the inning ended.
"I just said, what's your problem?" said Betts, whose three-run home run in the fourth inning had given the Dodgers the lead. "I don't know. I was just standing on deck. You have to ask him, I have no idea."
In the ensuing back-and-forth, García was ejected, as was Giants manager Gabe Kapler, who got into a heated argument with first base umpire Phil Cuzzi.
"At the time of the game and the score of the game and the inning, it didn't really make a lot of sense to a lot of us," said Trea Turner, whose fandom of the movie "The Wolf of Wall Street" was the origin of the Dodgers' head-tap routine, which copies a scene from the film.
Roberts said he was surprised by García's antics, noting almost every team has some hit celebration.
"Mookie is a guy that does everything the right way and has never had any intention to show any opponent up," Roberts said. "He was taken aback. He was shocked. As was I."
Betts said he had no prior history with García, other than facing him at the plate.
"I guess he felt a certain way," Betts said, more fired up during his postgame scrum than usual. "I don't know. You have to ask him."
García told reporters he wasn't trying to be disrespectful. Kapler, however, conceded his player "probably crossed the line in that situation."
Nonetheless, it wasn't long before the Dodgers were head-tapping again, when Turner hit a solo home run in the top of the seventh that helped put the game out of reach.
As Turner rounded third base — right in front of the Giants' dugout — he banged his helmet with his fist.
The Dodgers dugout erupted in an exaggerated version of the celebration, as well, a response Betts said "for sure" had extra motivation behind it.
"You started it," he said. "I'm not going to back down at that point. I'm not going to run away from it. I'm not going to encourage it, but I'm not going to run away."
