World No. 1 Lydia Ko birdied the 18th hole to cap a 2-under 70 in the third round Saturday that put her in the lead of the U.S. Women's Open, bolstering her chance for her third major title in less than a year.

The 19-year-old Ko became the youngest woman to win a major last year at the Evian Championship and followed that up by winning the ANA Inspiration this spring. Now she's in contention for her first U.S. Open title after failing to make the top 10 in her first four appearances.

Ko has a one-shot lead over 2009 winner Eun Hee Ji and Sung Hyun Park. Brittany Lang and Amy Yang are two shots back at 5 under and Angela Stanford is in sixth place at 4 under at CordeValle.