MIAMI: American Lexi Thompson, trying to extend her streak of LPGA seasons with at least one victory to eight, fired a seven-under-par 65 on Thursday to lead the Tour Championship by one stroke.

Thompson, who won the season finale in 2018, had a one-shot lead over Denmark's Nanna Koerstz Madsen, who fired a bogey-free six-under-par 66 at Tiburon Golf Club in Naples, Florida, to put herself in the mix for a first LPGA title.

Thompson, whose 14 LPGA titles include one major, jump-started her round with birdies at the second, third and fourth holes, and added another brace at the sixth and seventh.

She bounced back from a bogey at the tough par-four ninth with a birdie at the 12th before closing her round with back-to-back birdies at 17 and 18.

"It was great just being out here," said the Florida native, although the Covid-19 restrictions meant the usual group of family couldn't attend the event.

"It's a lot different," said Thompson, whose brother, Curtis, was on her bag. "But we're just happy to be playing this week and my brother and I had a lot of fun."

As in 2018, Thompson arrived at Tiburon in search of her first win of the season.

Coming off a missed cut last week at the US Women's Open, Thompson said she was more focused on cementing improvements to her game than stretching her streak of seasons with at least one victory.

"I was just overall very happy with how I committed to my shots.

That's what I've really been working on," she said. "I've been working so hard on my game in general trying to improve on it, and it's been kind of an up and down roller coaster with an unfortunate week last week."

Madsen opened her round with a birdie at the 10th, and surged up the leaderboard as she gained five shots in six holes around the turn.

Madsen, winner of one title on the Ladies European Tour, birdied the 15th, 16th and 17th and added birdies at the first and second before parring her way in for sole possession of second place.

Defending champion Kim Sei-young led a trio sharing third on five-under 67 alongside Germany's Caroline Masson and American Megan Khang.

World number two Kim arrived at Tiburon this year after a first major victory at the women's PGA Championship followed by a win at the inaugural Pelican Championship.

Three birdies and a bogey saw her make the turn at two-under, and she added three birdies coming home.

World number one Ko Jin-young headed a group of six players on 68.

Former No. 1 Park In-bee -- who holds a slight edge over Kim in the Player of the Year race -- opened with a first-round 71, as did American Danielle Kang, who is also in the hunt for Player of the Year honors after back-to-back wins earlier this year.