New Zealand's third-ranked Lydia Ko fired a bogey-free nine-under par 63 to seize a two-stroke lead after Thursday's opening round of the LPGA at Boca Rio.

The 24-year-old South Korean-born Kiwi, last year's Tokyo Olympic bronze medalist after taking silver in 2016 at Rio, made three straight birdies on both the front and back nines at the resort in Boca Raton, Florida.

American Danielle Kang, last week's winner at the LPGA Tournament of Champions in Orlando, was second on 65 with India's Aditi Ashok third on 66.

Ko birdied the par-5 10th to begin her round and reeled off three birdies in a row starting at the par-3 13th.

"I didn't have a great time on the putting green last week, so to kind of see putts going in was good imagery," Ko said. "I tried to feed off that for the rest of the round."

She made another trio of birdies to begin the front side of the course, birdied the par-3 sixth to seize the lead alone, then added another at the par-5 eighth.

"Overall, I didn't get into much trouble, was putting myself in play," Ko said. "When I had opportunity for birdie, for the most part I was able to hole it, which is nice."

Ko won last year's Lotte Championship in Hawaii for her 16th LPGA triumph and first tour victory since 2018. She also captured the Vare Trophy for low LPGA season scoring average and won the Saudi Ladies International on the Ladies European Tour.

Kang, seeking back-to-back titles after her sixth career LPGA triumph in last week's season opener, said she was able to recover well despite making only one bogey all day.

"I hit some bad shots out there. All you can do is go out and hit the next shot and try to do better," Kang said.

"Being mentally tough is something I've been working on and I'm very proud of my success, last week and today."

Kang birdied the first, third, sixth and eight holes of both the front and back nines while making her lone bogey at the par-4 fourth. She birdied three of four par-5 and par-3 holes on the 6,701-yard layout.

Kang captured the 2017 Women's PGA Championship winner for her only major title and is a two-time LPGA winner at Shanghai.

A fourth-place pack on 67 includes Japan's Yuka Saso and Nasa Hataoka, South Koreans Choi Hye-jin and Lee6 Jeong-eun, England's Charley Hull, American Gerina Mendoza and Canadian Maude-Aimee Leblanc.

Top-ranked defending champion Nelly Korda of the United States was in a group sharing 11th on 68.