Tiger Woods settled for a haphazard one-over-par 72 in the first round of the Genesis Invitational on Thursday as his surgically-repaired back caused him problems.

In his first PGA Tour start since April, Woods mixed five birdies with six bogeys including one at the last after he shanked his second shot into the trees, making the 15-times major champion drop his club in frustration.

“My back spasmed on it,” Woods said of his eight-iron shot on the par-four 18th at Riviera Country Club.

“It had been spasming over the last three holes and it just locked up on me and didn’t move, didn’t rotate.”

Woods, who underwent spinal fusion surgery in 2017, recovered nicely on his next shot, splitting two trees with a punch hook to find the green.

“A lot of good and a lot of indifferent,” Woods said of his round on a sunny day in Pacific Palisades.

“It was one or the other. I don’t know how many pars I had, wasn’t many. I was either making birdies or bogeys and just never really got anything consistent going today.”

The 48-year-old 15-times major champion, who withdrew before the third round of last year’s Masters because of a foot injury, said that issue was no longer a problem.

He did admit, however, that his leg, badly injured in a car crash two years ago, was sore.

“It’s nothing that we weren’t prepared for and we’ve got some work to do tonight and tomorrow,” Woods said.

The Genesis Invitational, one of the PGA Tour’s eight Signature Events this year, features a halfway cut and $20 million purse, including $4 million for the winner.

American Patrick Cantlay topped the leaderboard after carding a seven-under 64.

Woods, who has never won the event, is also serving as a tournament host this week.