Overnight leader and former U.S. Women's Amateur Champion Virada Nirapathpongporn only managed a 1-under 71 on Saturday. She is tied for second place with Nancy Scranton and Brandie Burton, both of whom shot 70s in round three. The trio is knotted at minus-12.
Jang first broke into red figures at the par-5 second when she reached the green in two with a 5-iron. She two-putted for birdie, then two holes later, hit a pitching-wedge to 6 feet to set up birdie.
She closed out her front nine in style with another pitching-wedge approach at the sixth. Jang knocked her second to 5 feet and converted the birdie putt. She added another birdie at No. 8 from 6 feet out to make the turn at 4-under 32.
Jang began her ascent up the leaderboard at the 11th when she hit a 6-iron to 10 feet. She ran that birdie putt in the cup, then hit another great 6-iron at the 13th. This approach rolled to 4 feet and she drained the birdie putt to reach 15 under par.
Jang got it to 16 under par at the 14th when her 15-footer found the bottom of the cup. Trouble loomed for the Women's British Open champion at Corning's closing hole.
She pushed her drive into the right rough at 18, then hit an 8-iron into a greenside bunker. Jang blasted out to 20 feet, and missed the par opportunity.
'I just don't like the 18th hole,' admitted Jang. 'I don't know why. When you come to the tee box, it looks really narrow, so I just don't like hitting the tee shot.
'Every single hole I hit it really good. If the tee shots are really good, that makes it easier, and putting was good too. On this course, that's what I needed.'
Jang has only her four-stroke victory last year at Royal Birkdale. She is ranked 10th in the world and is a little antsy to return to the winner's circle.
'After the win last year, I've been waiting,' said Jang. 'My swing is getting better and better. Just didn't make any putts. That helps, more than winning a tournament.'
Morgan Pressel (68), Laura Diaz (67) and Kris Tamulis (69) are knotted in sixth place at minus-10.
Beth Bader (67), Giulia Sergas (68), Meena Lee (70) and Mhairi McKay (70) share ninth place at 9-under-par 207.
Defending champion Jimin Kang shot a 3-under 69 and is part of a group tied for 36th place at minus-4.