New Zealand's Lydia Ko completed the Olympic medal set by claiming her first gold as she finished 10 under par at Le Golf National.

Ko won the silver medal at Rio 2016 before picking up bronze in Tokyo three years ago, but her victory in Paris also pushed her career total to 27 points required for a place in the LPGA Hall of Fame.

She was the joint leader going into the final day and built a five-shot lead on the back nine to put herself out of reach as her competitors dropped away, though she set up a nervy finish as she carded a one-under 71.

Germany's Esther Henseleit almost caught her as she hit a six-under 66 to shoot up the leaderboard to finish on eight under, coming out of nowhere to clinch the silver medal.

Xiyu Lin was almost forced into a play-off for bronze, but she birdied the final hole for a 69 to finish on seven under, one stroke ahead of fourth place.

Switzerland's Morgane Metraux had been Ko's co-leader at the start of the day, but it was a day to forget as her game collapsed, and she finished the event in 18th.  

Nelly Korda and Rose Zhang also struggled to maintain their momentum on Saturday, as Ko surged out of their sights on the leaderboard.

Chun In-gee shot a three-under 69 on Friday to extend her leading score at the Women's PGA Championship to 11 under – six strokes better than anyone else through two rounds.

The South Korean, who is a two-time major winner, led by five strokes after the first round, and extended that by one more with five birdies and two bogeys in her second trip around the course. In doing so, she is the only player to shoot both rounds in the 60s.

Leading the chasing pack at five under is Australian Lydia Ko and American Jennifer Kupcho, with Ko's 67 tying for Friday's round of the day along with Lexi Thompson.

Thompson sits in a tie for ninth at three under, along with recent U.S. Open winner Minjee Lee and China's Xiyu Lin.

Heading into the weekend there are 26 women below par, including representatives from Thailand, Northern Ireland, Japan, Finland, England and South Africa.

Not even a tropical storm could hold back Nelly Korda as the young American star held on for Olympic gold at Kasumigaseki Country Club.

The world number one golfer emerged triumphant from a fierce battle in the final round, winning by a single stroke from Japan's Mone Inami and New Zealand's Lydia Ko.

Inami fired a 65 and was the co-leader at 17 under until she bogeyed the last, finding a greenside bunker with her approach and failing to put the ball close, then missing her 20-foot par putt.

That meant Korda walked down the 18th knowing she was in pole position to take gold, albeit needing to keep an eye on Ko.

Both Korda and Ko found the green safely, each with an outside chance of birdie. Neither could sink that first putt, but Korda left herself a tap-in for the title and made no mistake.

The 23-year-old then was embraced by her sister Jessica, dancing across the green to offer a fond embrace.

Jessica Korda had fired a joint best-of-the-day 64 to finish in a tie for 15th, but it was Nelly's day to triumph.

The champion set herself up for this success with a 62 in round two, and consecutive rounds of 69 on Friday and Saturday took her over the winning line.

Play was briefly suspended with two holes left to complete for the front-runners, as the nearby storm caused a 49-minute delay just while the tension was ramping up.

But fears of a Saturday washout were allayed to ensure the tournament went the distance, and with gold on 17 under going to Korda, Inami took silver in a play-off when Ko bogeyed 18, the first extra hole.

Inami and Ko, who also made 65 in the final round, had finished tied on 16 under, one ahead of India's Aditi Ashok, whose closing 68 was not enough for a medal.

Korda's triumph meant the USA achieved a golf double, with Xander Schauffele having won the men's title.