LAKE BUENA VISTA, Fla. — Lydia Ko of New Zealand could only think about the putts that did not go in, perhaps because she was used to making so many.
Ko ran off four birdies on the front nine on Saturday for a 30, and it was enough to carry her to a five-under-par 66 and a share of the lead with Eun-Hee Ji of South Korea going into the final round of the L.P.G.A.’s season-opening Tournament of Champions.
Ji also was hot early, and two birdies early on the back nine gave her a 66. She and Ko were at 13-under 200.
Brooke Henderson of Canada was poised to make it a three-way tie until she made bogey on the par-3 closing hole for a 69, leaving her one shot behind. Nelly Korda had an eagle and four birdies for a 65 and was two shots off the lead.
Ko, who made par on the final seven holes, said: “I felt like there were a few putts that I thought I holed and it didn’t go in. But I holed a really long one on 8 — that one, I probably didn’t deserve — so everything balances out.”
She added, “All I can do is put a good roll on it and just give myself good opportunities out there.”
Now she has an opportunity to start 2019 by winning, which took her until April to do last year as she began to emerge from a slump.
The event is limited to winners each of the last two seasons for a $1.2 million purse. It includes a 49-player field of celebrities and athletes competing for a $500,000 purse. The Hall of Famer John Smoltz had 39 points in the modified Stableford format, giving him a four-point lead over another former pitcher, Mark Mulder.
Ko said she had been enjoying the interaction with athletes, perhaps a little too much.
“You don’t know what time it is out there, you’re just having a really good time,” she said. “I’ve never been caught up in what position I am and what I need to do. I probably need to do that a little bit more tomorrow.”
Ariya Jutanugarn of Thailand, the top-ranked player in the world, failed to make a birdie in her round of 75 and fell nine shots behind. Stacy Lewis, who gave birth three months ago, bounced back from a 74 to post a 66. She was six shots behind.
“I feel like the touch and the feel is coming back,” said Lewis, competing for the first time in six months. “I still hit some weird golf shots, which is fatigue, I think, more than anything. Got pretty tired toward the end of the round yesterday.”
The forecast for the final round was cooler temperatures in the upper 50s, and 20-mile-per-hour wind with gusts, which is fine with Henderson.
“I think I can grind it out, and a lot of my wins have come in windy conditions,” she said.