World No 1 Lydia Ko carded a two-under 70 to take a one-shot lead after the third round of the US Women's Open in San Martin, California.

The 19-year-old New Zealander was in a four-way tie for the lead heading down the 18th but she drained a nine-foot birdie putt to edge ahead on seven-under 209.

Ko has a one-shot cushion over 2009 champion Eun Hee Ji and halfway leader Sung Hyun Park of South Korea with American Brittany Lang and Korean Amy Yang a further shot adrift on five under at CordeValle.

Sweden's Anna Nordqvist (73) is the leading European in a tie for 15th place on one under, with Scotland's Catriona Matthew (71) and England's Jodi Ewart Shadoff (75) one shot further back.

Ko made a shaky start to the tournament when she was tied for 52nd place after an opening 73 but got into contention with a second-round 66 before moving into the lead for the first time on Saturday.

She made a long downhill putt for birdie on the third but dropped a shot on the ninth before further birdies on the 13th and 18th.

The only other time Ko has held the lead heading into the final round of a major she was beaten in a play-off by Canada's Brooke Henderson at last month's KPMG Women's PGA Championship.

"I think the biggest key around today - well, the biggest difference was the wind. I know it was breezy from the mornings. I knew that it would play a lot tougher than yesterday, because the majority of my round yesterday was played in calm weather," Ko said.

"So people, they say it's moving day on Saturday, but it was really tough out there, because the course is drying out, firming up. And it was tough to get near the pins on some holes."

POS

From Sky Sports