Hannah O'Sullivan

O’Sullivan, 17, of Chandler, Ariz., rolled to a 7-and-6 win over Justine Dreher in Thursday morning’s Round of 32 and followed that with a 4-and-3 victory over Jennifer Kupcho in the afternoon’s Round of 16.

“I'm feeling really good about my game,” said O’Sullivan, who also notched a 7-and-6 victory in Wednesday’s Round of 64. “I'm just trying to be as confident as possible and taking it one shot at a time. It's been working out pretty well.”

Kupcho presented O’Sullivan, the 2015 U.S. Women’s Amateur Four-Ball Championship co-runner-up, with her first true challenge of the championship. O’Sullivan built a 4-up lead through nine holes. Kupcho’s birdie on the par-4 10th led to O’Sullivan’s first lost hole of the championship, but O’Sullivan swiftly rebuilt an insurmountable 5-up lead with wins at holes 12 and 13.

“A 3-up lead can go away so quickly,” said O’Sullivan, who is attempting to better her U.S. Women’s Amateur result from 2014, when she fell in the semifinals to eventual runner-up Brooke Mackenzie Henderson. “I just know that you have to end it as quickly as possible and try to keep pushing and try not to give them a chance.”

Next up for O’Sullivan is Lindsey McCurdy, 20, of Liberty Hill, Texas. The junior at Southern Methodist University knocked off 2014 U.S. Women’s Amateur champion Kristen Gillman, 4 and 3, in the Round of 32 and earned a 1-up win over the University of Oregon’s Caroline Inglis in the Round of 16.

Two-time Great Britain and Ireland Curtis Cup competitor Bronte Law, 20, of England, faced two tough opponents in 2015 NCAA Division I Women’s Golf Championship runner-up Gaby Lopez and 2015 U.S. Girls’ Junior champion Eun Jeong Seong. But Law, a junior at UCLA, was more than up to the challenge, dispatching Lopez, 2 and 1, before cruising to a 4-and-2 win over Seong.

“I've learned from match-play experience that you have to treat every single opponent equally because someone has their hot day, someone doesn't,” said Law, the No. 2 player in the Women’s World Amateur Golf Ranking™. “I don't treat anyone differently out there on the course.”

Law is attempting to become the third English-born winner of the U.S. Women’s Amateur, joining Pamela Barton (1936) and Gladys Ravenscroft (1913). She will meet Sierra Brooks on Friday. Brooks birdied the par-5 18th to earn a 1-up win over Hailee Cooper in the Round of 32, and needed 20 holes to dispatch Maddie McCrary in the Round of 16.

Anna Newell squeaked into the Round of 16 after surviving a 25-hole marathon with Peru’s Lucia Gutierrez Ballon. Newell, 19, of Tampa, Fla., missed a birdie putt on the first extra hole that would have closed out the match, but her birdie on the seventh extra hole finally earned her a berth in the next round. It was the third 25-hole match in championship history and first since 2009. Newell then only needed 17 holes to dispatch Bailey Tardy, 2 and 1, in the afternoon’s Round of 16.

Newell’s next opponent is Mathilda Cappeliez, 17, of France. Cappeliez, who tied for 59th in the 2014 U.S. Women’s Open, notched 4-and-3 and 3-and-2 wins over Kenzie Neisen and Elizabeth Wang, respectively. Cappeliez is trying to join 1969 U.S. Women’s Amateur champion Catherine LaCoste as the only two Frenchwomen to capture the championship title, and could become just the third French champion in USGA history.

Rounding out the Women’s Amateur quarterfinalists are Bethany Wu and Mika Liu, who will meet in Friday afternoon’s final match. Wu, 18, of Diamond Bar, Calif., beat Laura Restrepo by a 3-and-1 margin in the Round of 32 and earned a 5-and-4 win over her future UCLA teammate, Lydia Choi, in the Round of 16. Liu, 16, of Beverly Hills, Calif., took a 1-up Round of 32 win over Mariel Galdiano and followed that with a 4-and-3 win over Cindy Ha in the Round of 16.

With a victory in Sunday’s 36-hole final match, Liu could become just the third woman to win two USGA championships in the same season. Liu captured the 2015 U.S. Women’s Amateur Four-Ball Championship title in May with partner Rinko Mitsunaga. Only Pearl Sinn (1988 Women’s Amateur and Women’s Amateur Public Links) and Jennifer Song (2009 Women’s Amateur and Women’s Amateur Public Links) have completed the double.

The 2015 U.S. Women’s Amateur Championship is open to female amateur golfers with a Handicap Index® not exceeding 5.4. It consists of 36 holes of stroke play followed by six rounds of match play, with the championship scheduled to conclude with a 36-hole final on Sunday, Aug. 16.

The match-play rounds of the 2015 U.S. Women’s Amateur Championship will be broadcast on Fox Sports 1. Coverage will be from 4 p.m. to 7 p.m. EDT every day through Sunday, Aug. 16. Additionally, bonus coverage will be streamed live on usga.org on Aug. 16 from Noon to 2 p.m. EDT.

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