Dodgers pitcher Clayton Kershaw said his latest back injury is “not too serious and getting better quickly.”

Kershaw missed Thursday’s Opening Night start after developing stiffness while doing the same core exercises he said he’s been doing for the last 1 1/2 years. After receiving treatment on Friday, he played catch to 90 feet and “felt pretty good.”

This is the second consecutive season Kershaw has begun a season on the 10-day injured list and the fourth time he has been sidelined by a back injury. His previous back stints sidelined him for 10, five and three weeks, but he said this one is not similar to the 10-week ordeal he experienced in 2016, when he suffered a herniated disk.

“I’m optimistic it shouldn’t be much longer than my original [10-day] stint on the IL,” he said. “I don’t really remember each specific time, other than when I really hurt it in 2016. That’s the only one I truly remember being in serious, serious pain. I feel like every other one ... back pain you just deal with and things crop up. I’ve been fortunate the last few years but unfortunately something cropped up Tuesday. But not super serious and thankful I should be back pretty quick.”

Kershaw said he was thankful that a Tuesday MRI came back clean with no structural damage, clearing him for immediate rehab. He is eligible to return next Friday.

“I felt so good going into the season, it was pretty defeating,” he said. “Like, how is this happening right now? But I started moving forward yesterday [and] today made a lot of progress.”

For now, manager Dave Roberts said rookie right-hander Dustin May is penciled in to make what would have been Kershaw’s next scheduled start, on Wednesday in Houston. May stepped in Thursday with a sometimes-electric 4 2/3 innings in the Dodgers’ 8-1 win over the Giants.

“We just don’t know right now,” Roberts said of his future rotation. “We’re hoping Clayton after Houston, but we haven’t penciled in Dustin for that start yet. But it’s certainly a good chance.”

Kershaw said Opening Night was multiple levels of “weird.”

“Not being able to pitch, not being able to sit in the dugout and all these different things,” he said. “But, at the end of the day, it was still baseball. We played another team, we won a game. That felt pretty good; from where we thought we might not get to, to get to that point, I think, is a testament to the game.

“I heard somewhere the ratings were the best it’s been in a while, so I think the country was thankful we were able to play baseball. My family was super excited to watch a game that meant something. I think there were a lot of positives that it came to fruition in whatever way that it did.”

Worth noting

Roberts clarified his lineup approach, saying he will alternate right-handed and left-handed batters throughout the lineup but will lead off with Max Muncy against right-handers and Mookie Betts against left-handers.