Cleveland, OH (Sports Network) - Lydia Ko, the top-ranked amateur in the world, fired a 6-under 66 on Monday to grab a 2-shot lead after the first round of stroke play at the U.S. Women's Amateur Championship.

The 66 for Ko, who was the co-medalist last year, was the second-lowest qualifying score recorded in this championship. She also shot 66 last year before losing in the second round of match play.

"I've been playing really well. I've been doing my best not to grind. Just rest, keep my energy up. I played really freely today," Ko stated.

Alison Lee, this year's Girls Junior champion, and Hyo-Joo Kim, the third- ranked women's amateur in the world, share second place at minus-4 at The Country Club.

Brooke Mackenzie Henderson is alone in fourth after a 3-under 69. Austin Ernst, who was a semifinalist last year, carded a 70 and was joined in fifth place by McKenzie Neisen, Natalie Gleadall, Alina Ching and Kelly Shon.

Ariya Jutanugarn, the second-ranked women's amateur in the world, is among those tied at 1-under 71. Her sister, Moriya, who was the runner-up last year to Danielle Kang, stumbled to 2-over 74.

The Sports Network