Jennifer Hahn

Hahn, 21, of Henderson, Nev., carded an opening birdie on the par-5 10th, her first hole, but three straight bogeys put her in an early hole. She responded with six birdies over her remaining 14 holes to earn a spot atop the leader board.

“I just thought of it as a brand new opportunity, a brand new nine, so I just stuck to my game plan,” said Hahn, a rising senior at Vanderbilt University. “My approach shots were better and the putts were dropping.”

Wagner, 18, of Windermere, Fla., also started on No. 9 and played her first nine holes at even par. Her inward nine, however, was a different story. Four birdies brought the incoming University of Florida freshman into the clubhouse tied for the lead.

“I hit 14 greens today, and I kept giving myself opportunities,” said Wagner, who competed in her first U.S. Women’s Open last month at Lancaster (Pa.) Country Club. “I think I just kind of got into a rhythm.”

Cindy Ha, 18, of Demarest, N.J., closed her 3-under 69 with a clutch 10-foot birdie putt, one she called “one of the toughest putts that I've ever had,” at the ninth hole. Ha, who reached the semifinals of the 2014 U.S. Women’s Amateur Public Links and U.S. Girls’ Junior championships, sits in solo third after a round that boasted seven birdies and four bogeys.

“You don't have to play a perfect game to have a good score,” said Ha, a rising sophomore at Vanderbilt University. “You just need to kind of adjust and adapt to the surroundings and adapt to the circumstances, and that's what I did really well today.”

A quartet of players sit at 2-under 70, led by 2014 USA Curtis Cup Team member Mariah Stackhouse, 21, of Riverdale, Ga. Stackhouse, who earned the winning point for Stanford University in the 2015 NCAA Division I Women’s Golf Championship, knew from her first practice round that Portland Golf Club suited her game, and she set a lofty goal that matched her confidence.

“I realized that the best thing to do is get a good seed so you don't start off having to really fight the whole way through,” said Stackhouse, whose three birdies on Monday included a tap-in on the par-4 14th. “My goal coming in for the week was to play good stroke-play rounds. I've got one round out of the way, so we'll see what my game brings me tomorrow.”

Stackhouse is joined in a tie for fourth by Mathilda Cappeliez, 17, of France, who made the cut in the 2014 U.S. Women’s Open; Mariel Galdiano, 17, of Pearl City, Hawaii, who last week captured the 2015 Canadian Women’s Amateur Championship; and 2013 Australian Amateur runner-up Soo Jin Lee, 19, of Australia.

Reigning U.S. Women’s Amateur champion Kristen Gillman opened her title defense with a 1-under 71 to tie for eighth. The 17-year-old from Austin, Texas, carded three birdies and two bogeys for what she called a “solid, steady round.”

“I tried as hard as I could not to add any pressure,” said Gillman, whose whirlwind year since capturing the Women’s Amateur has included appearances in three LPGA major championships and competitions in six countries. “[I just wanted to] come out here and have fun and just enjoy being able to have that title on my back.”

Gillman is attempting to become the first repeat Women’s Amateur champion since Danielle Kang achieved the feat in 2010 and 2011.

Bethany Wu, the No. 2 player in the Women’s World Amateur Golf Ranking™ and the 2014 Women’s Amateur stroke-play medalist, carded two birdies and a bogey to join Gillman at 71. They are joined by eight other players, including 2014 Mexican Women’s Amateur champion Maria Fassi, 2015 U.S. Women’s Open competitor Muni He and 2015 U.S. Girls’ Junior runner-up Angel Yin.

Five players started play on Monday without a practice round at Portland Golf Club after competing in last week’s LPGA Qualifying Tournament Stage I at Mission Hills Country Club in Rancho Mirage, Calif. Nelly Korda, the 17-year-old sister of LPGA star and 2010 U.S. Women’s Amateur runner-up Jessica Korda, followed her third-place performance at Mission Hills with a 1-over 73 at Portland Golf Club. Gaby Lopez, who joined Korda in making the cut into Stage II, carded a 74, while Justine Dreher, Joo Youn Seo and Elizabeth Tong, who did not advance to Stage II, returned scores of 76, 77 and 74, respectively.

Six-time USGA champion Ellen Port, the championship’s oldest competitor at age 53, made the turn at 1-over par after draining a short birdie putt on the par-4 ninth. However, a bogey and two double bogeys on her inward nine dropped the 2014 USA Curtis Cup Team captain to 5-over 77. Port was recently named the head women’s golf coach at Washington University in her hometown of St. Louis, Mo.

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 on Aug. 12-16. Additionally, bonus coverage will be live streamed on usga.org on Aug. 13 and 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.