SAN FRANCISCO • World No. 1 Lydia Ko, seeking to add a third Major golf title to her resume, birdied the 18th hole to take a one-shot lead after three rounds of the US Women's Open on Saturday.

The young New Zealander had three birdies and one bogey on a blustery day on the CordeValle course in San Martin, California - her two-under 70 giving her a seven-under total of 209 and a one-stroke lead over South Koreans Park Sung Hyun and Ji Eun Hee.

Park, a five-time winner on the Korean LPGA Tour who is playing in her first US Open, held a two-stroke overnight lead.

She carded a two-over 74 to join Ji, who signed for a 70, on 210.

South Korean Amy Yang carded a 73 to share fourth with American Brittany Lang (68) on 211.

Ko won the Evian Championship last year and the ANA Inspiration this year to take her Major tally to two at the age of 19. A victory would make her the youngest three-time Major champion, man or woman, ever.

She had surged into contention with a 66 on Friday, but said conditions were less conducive a day later. "It was really tough out there," Ko said. "The course is drying up, firming up. It was tough to get near the pins on some holes."

But the poised teenager stayed steady on a day that saw as many as four players share the lead, and rolled in a 10-foot birdie putt on the par-five 18th to break out of a three-way tie for first with 2009 champion Ji and Park.

She said: "Winning the Evian Championship gave me a lot of confidence to say, 'Hey, I can play well at these Majors'.

"And winning the ANA at a course where I hadn't really played well before gave me another boost of confidence. Every time I play a Major, I am always learning from that."

While all eyes would be on Ko, she cautioned that plenty of players would be in with a chance.

"There's still a lot of golf to be played," she said. "There's a past US Open champion just a shot behind."

And two strokes back there was Yang, who had at least a share of the 54-hole lead in each of the last two US Women's Opens but finished runner-up to Chun In Gee of South Korea last year and settled for fourth in 2014 behind winner Michelle Wie.

She held a share of the lead before a bogey at the 17th, but said she could not be disappointed with her one-over effort.

Yang said: "I saved some good up-and-downs. I'm still hitting it good. So I'm looking forward to it."

REUTERS, AGENCE FRANCE-PRESSE