Lydia Ko has gone from the highs of winning her first tournament in nearly three years to shooting her worst round of the season.

The 23-year-old Kiwi carded a seven-over par 78 in the opening round of the LA Open in California, leaving her with a huge task to make the cut into the weekend.

Ko's round featured two double bogeys, four bogeys and a solitary birdie.

It was her worst round since August 1, 2019, when she shot an eight-over 80 at the British Open.

Ko took out the Lotte Championship in Hawaii on Monday after a dominant seven-under par 65 in the final round to take the title by seven shots.

The win shot her up to seventh in the world rankings and 13th all-time on the LPGA career money list.

However, she struggled to replicate that form on Thursday to sit 14 shots behind American Jessica Korda.

Korda birdied three of the final four holes for a seven-under 64 and a one-stroke lead.

Korda had eight birdies and a bogey at Wilshire Country Club to match the tournament scoring record set by Megan Khang and Annie Park in 2019.

"This isn't an easy golf course at all," Korda said. "I was lucky to be able to position myself in the right spots off the tee and take advantage of the short putts that I did have for birdie."

Korda won the season-opening Diamond Resorts Tournament of Champions in January for her sixth LPGA Tour title, and sister Nelly Korda followed with a victory a month later in the Gainbridge LPGA in the second event of the year.

"We're not playing in Asia next two weeks," Jessica Korda said. "Taking those three weeks off, and the summer is so busy. Just going to pace ourselves. Got some big events coming up that I would like to be prepared for, and that's kind of what my team and I are concentrating on."

Tiffany Chan and Moriya Jutanugarn were a stroke back. Chan played at Southern California.

"My goal was to try not to be too aggressive because it's my home course so I know the course really well," Chan said. "So, I still tried to be a little more conservative."

Nelly Korda was two strokes back at 66 with Dana Finkelstein, Su Oh, Carlota Ciganda and Austin Ernst.

Michelle Wie West matched Lexi Thompson with a 70.

Patty Tavatanakit had a 75 in her first event since narrowly beating Ko at the ANA Inspiration for her first major and first LPGA Tour victory.

- with AP