SAN MARTIN, Calif. — When Sung Hyun Park entered her first U.S. Women’s Open, her goals were modest. Halfway through the tournament, Park has put herself in prime position to contend.

Park capitalized on the favorable morning scoring conditions, shooting a 6-under 66 Friday to take a two-stroke lead after the second round.

“I didn’t even think about winning because this is the first time for me,” Park said through an interpreter. “I would like more experience with the USGA, LPGA. But I’m trying to enjoy this tournament. That’s why I am just more comfortable, don’t even think about the winning, I just enjoy the play.”

Park, a 22-year-old from South Korea, made her LPGA debut last year when she finished second at the KEB-HanaBank Championship in South Korea. She has played three LPGA tournaments this year, tying for sixth in her first major at the ANA Inspiration in the spring.

Park had four birdies in a six-hole span to move to 9 under before struggling on the final two holes. She hit her second shot into the greenside bunker at the par-4 17th and then missed a short par putt for her only bogey of the round. Park then drove into a hazard on the par-5 18th for a one-shot penalty before saving par with a 15-foot putt.

Amy Yang shot a 71 to get to 6 under, tied for second with first-round leader Mirim Lee. World No. 1 Lydia Ko bounced back from a 1-over first round to shoot 66 and move into a tie for fourth with Haru Nomura.

Lee, who tied a U.S. Open record by shooting 8 under Thursday, birdied three of the final four holes on her front nine in the afternoon. But things then quickly fell apart. She missed the fairway with her drive on the par-4 10th and her approach shot sailed past the green. Her chip attempt fell short of the green before she three-putted from the fringe for a double bogey.

Lee then drove into the front bunker on the par-3 12th hole before missing an 8-foot putt for par.

Ko got off to a shaky start with a bogey on the first hole before stringing together four straight birdies starting at No. 3. She added two more birdies before capping her round with another on the 18th.

“My birdie on 3 kind of turned the round around, and making the string of birdies definitely helped,” she said. “Just to know that this is the first time I was under par for the tournament kind of put myself in a positive position.”

CHAMPIONS TOUR: Scott Dunlap made four birdies in a five-hole span on the front nine, then reeled off five straight birdies to start the back nine en route to an 8-under 64 in the opening round of the Dick’s Sporting Goods Open in Endicott, New York.

Glen Day, Bart Bryant and John Riegger were tied for second at 66 after the first round.

EUROPEAN TOUR: Alex Noren of Sweden took advantage of calmer conditions to shoot a 6-under 66 and take a one-stroke lead at the Scottish Open.

Danny Lee of New Zealand (66) and Eddie Pepperell of England (67) were a shot behind Noren, who had an 8-under 136 total after two rounds.

Phil Mickelson and Henrik Stenson, two of the most well-known players in the field, made the cut after shooting rounds of 69 but were nine shots off the lead.