Cleveland – Lydia Ko, 15, of New Zealand, the world’s No. 1-ranked amateur, advanced to the quarterfinals in the 2012 U.S. Women’s Amateur by winning two matches on Thursday, while medalist Hyo-Joo Kim, of Korea, was defeated in the third round at the 6,512-yard, par-72 course at The Country Club.

Ko scrambled out of deep rough on the 18th hole to outlast Celine Boutier, 18, of France, 1 up, in the round of 16. Nicole Zhang, 20, of Canada, defeated Kim, 1 up.

Two Americans remain in the field:  Erynne Lee, 19, of Silverdale, Wash., and Jaye Marie Green, 18, of Boca Raton, Fla.

Match-play rounds continue on Friday with the four quarterfinal matches, with a 36-hole final scheduled for Sunday.

The U.S. Women’s Amateur is one of 13 national championships conducted by the United States Golf Association, of which 10 are strictly for amateurs.

Leading by one hole,  Ko drove deep into the right rough on the 18th hole of her match with Boutier. The French player followed by hitting safely to the back of the green from the middle of the fairway. With a good lie and the match on the line, Ko aimed at the green with a pitching wedge. She missed it left and short, but avoided a greenside bunker.

Ko chipped to within 4 feet of the hole. When Boutier failed to make a 35-footer for birdie, Ko stroked the putt into the middle of the hole for the halve and the win.

“It was lucky,” said Ko, the low amateur at last month’s U.S. Women’s Open. “If I go in that bunker, it’s a hard shot.”

It was the second tough match Ko survived on Thursday. In the morning’s second round she defeated Amy Anderson, 20, of Oxbow, N.D., a 2012 USA Curtis Cup player and the 2009 U.S. Girls’ Junior champion, 3 and 2.

Zhang ended Kim’s hopes. Neither player led by more than one hole. Zhang took a 1-up lead at the 10th. Kim, playing in her first national match-play championship, won the 11th with a birdie, but the superb iron play she had used all week failed her in the closing holes. Zhang took the 13th with a par to go 1 up and held on to win by the same margin.

After morning rain softened the course, Zhang was hitting longer shots into the greens than she had all week. On holes where she had hit 7-irons under dry conditions, she was forced to use a 5-wood.

“I found it a lot more difficult because it was so wet,” Zhang said. “I managed to get it up and down and I’ve definitely liked my game the last few days.”

With the usual match-play concessions, Su-Hyun Oh, 16, of Australia, had the best scoring day. She was nine under par for 14 holes in her second-round 5-and-4 win Thursday morning over Maia Schechter, 19, of Takoma Park, Md. Oh defeated Jayvie Marie Agojo, 26, of the Philippines, in the third round, 4 and 3, and was two under par for the 15 holes.

This is Oh’s first start in the U.S. Women’s Amateur. “My goal was top 16,” she said. “Now, I’ll try to go as far as I can. My iron play was the best of my golf career. These are the best scores I’ve ever shot.”

In her morning match against Schechter, Oh nearly aced the 170-yard, par-3 ninth with a 5-iron, leaving it inches from the hole. On the 12th, she holed an 8-iron from 134 yards for an eagle-3.

Paula Reto, 22, of South Africa, became the oldest quarterfinalist when she defeated Jessica Vasilic, 16, of Anaheim Hills, Calif., 4 and 2. With Vasilic in the bunker, Reto was conceded an eagle-3 at the par-5 16th hole to win the match.

Reto’s short game kept her in the match. “I was a little all over the place today,” she said. “If I can just focus on my game and nobody else’s, I’ll be ok.”

Marijosse Navarro, 15, of Mexico, also advanced to the quarterfinals with a 3-and-1 victory over Madeleine Sheils, 22, of Boise, Idaho. Navarro won the Mexican Women’s Amateur, a stroke-play event, in 2010 and 2012.

Green defeated 2012 USA Curtis Cup player Lisa McCloskey, 21, of Houston, 2 up, in the third round.

Erynne Lee, the other remaining American, defeated Austin Ernst, 20, of Seneca, S.C., 2 and 1. Austin was a member of the 2012 USA Curtis Cup Team and the 2011 NCAA individual champion. Lee, an incoming sophomore at UCLA, advanced to the semifinals of the 2008 U.S. Women’s Amateur.

Against Ernst, Lee’s momentum came from a birdie at the 13th. She was 1 down when she fired her iron shot to within 3 feet of the hole, made the putt and squared the match.

“I started dialing in my shots,” Lee said. “Most of my irons were within 10 feet of the hole after that. My game has been on the last two days. Everyone’s dream is to be here and win the championship. I’m just glad to be here and see where it takes me.”

All eight quarterfinalists are exempt into the 2013 U.S. Women’s Amateur at the Country Club of Charleston.    

Results

Cleveland – Results from Thursday morning’s second round of match play at the 2012 U.S. Women's Amateur Championship, being conducted at the 6,512-yard, par-72 course at The Country Club:

Upper Bracket
Hyo-Joo Kim, Korea (136) def. Isabelle Lendl, Goshen, Conn. (146), 2 and 1
Nicole Zhang, Canada (144) def. Cyna Rodriguez, Philippines (143), 4 and 3
Jayvie Marie Agojo, Philippines (145) def. Natalie Gleadall, Canada (141), 1 up
Su-Hyun Oh, Australia (144) def. Maia Schechter, Takoma Park, Md. (149), 5 and 4
Andrea Lee, Hermosa Beach, Calif. (149) vs. Jaye Marie Green, Boca Raton, Fla. (146)
Lisa McCloskey, Houston, Texas (142) def. Lauren Diaz-Yi, Thousand Oaks, Calif. (144), 4 and 3
Madeleine Sheils, Boise, Idaho (149) def. Ashlan Ramsey, Milledgeville, Ga. (145), 1 up
Marijosse Navarro, Mexico (149) def. Lee Lopez, Whittier, Calif. (148), 1 up

Lower Bracket
Lydia Ko, New Zealand (137) def. Amy Anderson, Oxbow, N.D. (146), 3 and 2
Celine Boutier, France (143) def. Karen Chung, Livingston, N.J. (148), 1 up
Jessica Vasilic, Anaheim Hills, Calif. (147) def. Diana Fernandez, Paraguay (149), 6 and 5
Paula Reto, South Africa (141) def. Bronte Law, England (147), 2 and 1
Ariya Jutanugarn, Thailand (139) def. Bethany Wu, Diamond Bar, Calif. (145), 6 and 4
Ashlee Dewhurst, Australia (144) def. Breanna Elliott, Australia (143), 20 holes
Austin Ernst, Seneca, S.C. (147) def. Sarah Beth Davis, Victoria, Texas (149), 3 and 2
Erynne Lee, Silverdale, Wash. (149) def. Elisabeth Bernabe, Anaheim Hills, Calif. (144), 2 and 1

Cleveland – Results from Thursday afternoon’s third round of match play at the 2012 U.S. Women's Amateur Championship, being conducted at the 6,512-yard, par-72 course at The Country Club:

Upper Bracket
Nicole Zhang, Canada (144) def. Hyo-Joo Kim, Korea (136), 1 up
Su-Hyun Oh, Australia (144) def. Jayvie Marie Agojo, Philippines (145), 4 and 3
Jaye Marie Green, Boca Raton, Fla. (146) def. Lisa McCloskey, Houston, Texas (142), 2 up
Marijosse Navarro, Mexico (149) def. Madeleine Sheils, Boise, Idaho (149), 3 and 1

Lower Bracket
Lydia Ko, New Zealand (137) def. Celine Boutier, France (143), 1 up
Paula Reto, South Africa (141) def. Jessica Vasilic, Anaheim Hills, Calif. (147), 4 and 2
Ariya Jutanugarn, Thailand (139) def. Ashlee Dewhurst, Australia (144), 3 and 2
Erynne Lee, Silverdale, Wash. (149) def. Austin Ernst, Seneca, S.C. (147), 2 and 1

Pairings

Cleveland – Pairings for Friday’s quarterfinal round of match play at the 2012 U.S. Women's Amateur Championship, being conducted at the 6,512-yard, par-72 course at The Country Club (All times EDT):

Upper Bracket
12:45 p.m.       Nicole Zhang, Canada (144) vs. Su-Hyun Oh, Australia (144)
12:55 p.m.       Jaye Marie Green, Boca Raton, Fla. (146) vs. Marijosse Navarro, Mexico (149)

Lower Bracket
1:05 p.m.         Lydia Ko, New Zealand (137) vs. Paula Reto, South Africa (141)
1:15 p.m.         Ariya Jutanugarn, Thailand (139) vs. Erynne Lee, Silverdale, Wash. (149)