If Shin wins, it will be her fifth victory in the last 11 months and second of the year.
ROCHESTER, N.Y. (AP) -- To dispel her jitters, Jiyai Shin reached for a sandwich.
The South Korean star, seeking her fifth win in 11 months, shot a 5-under 67 on Saturday to extend her lead to four strokes at the Wegmans LPGA.
"On the front nine, I lost my confidence," the 21-year-old Shin said of a slow start. "I tried eating. Eat some bread on No. 10 and then I made birdie."
With five of her six birdies on the back nine, Shin moved to 16-under 200 after three rounds. Morgan Pressel, a two-time winner on tour whose season-best finish was a tie for seventh in April, shot a 70 and was in second place at 12 under -- one better than rookie Stacy Lewis, who also shot 70.
Cheyenne Woods, the niece of Tiger Woods, missed the cut by four strokes in her professional golf debut. Woods and 70 other players completed their second rounds Saturday morning after play was interrupted by thunderstorms Friday. Defending champion Eun-Hee Ji could only manage a 71 and crashed at 7 over.
In 2008, Shin became the first non-LPGA member to win three events. A multiple winner on the Korean tour, she reeled in the Women's British Open last August, then followed with late-season wins in the Mizuno Classic and ADT Championship. In March, she captured the HSBC Women's Champions in Singapore for her first victory as a tour member.
Shin rolled in a 20-foot birdie putt on No. 1, but she failed to reach the par-4 sixth in two and missed a 6-foot par putt for her only bogey at Locust Hill, a traditional, tree-lined course with compact, undulating greens.
After failing to hit a succession of greens in regulation, Shin made amends by chipping in from 15 yards on the par-4 10th and left her approach shot inches away for another birdie on the next hole. She curled in a birdie from 7 feet on No. 14, another from 4 feet on No. 16 and her sixth from 5 feet on the par-5 17th.
Pressel sank a 15-foot birdie putt on No. 8 to get a brief share of the lead.
"Being in second spot is never a bad spot unless it's the end of the tournament, so I still have a chance," Pressel said. "I have to go very, very low. She (Shin) is very steady ... so I've got to go for birdies."
Lewis, the former NCAA champion from Arkansas who tied for third at the U.S. Women's Open last summer, lipped out from inside 2 feet on three holes before chipping in for eagle on the 11th from 39 yards.
First-round leader Sandra Gal of Germany (69) was tied for fourth at 10 under with Lindsey Wright (67) of Australia, who recorded a career-best second place at the LPGA Championship two weeks ago. South Korean Sun Young Yoo (69) was in sixth.
South Korean rookie Haeji Kang shot 65, the day's best, to get to 8 under. Michelle Wie fell out of contention with a 75.
The 18-year-old Woods, who competed on a sponsor exemption, finished at 5-over 149 -- four strokes above the cutline.
"I could have made a couple more birdies -- or not as many bogeys -- but I'm happy," she said. "Three more years at Wake Forest and then hopefully I'll be back out here."
Ranked 93rd among college golfers, Woods got to 2-under -- and 1-over total -- through 10 holes before darkness ended play Friday. She opened with a par Saturday morning, then drove into trees, lost her ball and made a triple-bogey at the par-4 12th.
"I lost my drive to the right on 12 and we couldn't find it in the rough," she lamented as dozens of fans lined up for autographs. "There was a spotter there, he heard it drop but he never saw it. We were looking around all over but we never found it."
Woods finished up the tournament by making an 8-foot putt for birdie.
"My goal was to make the cut, but I thought I played well for the most part," she said, masking her disappointment with a smile similar to her famous uncle's. "I was ... comfortable out there and then, I don't know, I just had a lot of fun and just tried to take in the moment."