Zhang's 63 leaves Korda plenty to do at Founders Cup
Zhang's bogey-free round leaves world number one Korda with plenty of work to do if she is to mount a bid for an LPGA record sixth consecutive victory.
Korda's three-under 69 left her six shots behind the leader at Upper Montclair Country Club in Clifton, New Jersey.
The 25-year-old American equalled Annika Sorenstam and Nancy Lopez for the all-time record win streak of five in five starts by taking last month's Chevron Championship, beating Sweden's Maja Stark by two strokes in the year's first women's major championship.
After a two week break, she was quickly into her stride with a birdie on the par-5 second and the par-5 ninth but after another birdie on the 12th she bogeyed the par-4 13th.
Korda's round ended on a positive note with birdie on the final hole and she was happy with a solid return.
"There is still three more days. You still have a lot of things....I know the weather is not supposed to be great and there is just different factors that go into the rest of the tournament," she said.
"So it's definitely nice to get a good round in. Still a long, long ways away from Sunday," she said.
"Overall a solid day. Didn't really make too many mistakes, and if I did - this golf course is very, very narrow off the tee - I kind of gave myself a good chance at par.
"So definitely got bailed out with my short game a couple times. Overall, it was a solid day," she added.
Zhang, however, received full rewards for her outstanding front nine, where she made six birdies including four in a row before reaching the turn.
She also left the course with the boost of a birdie on the 18th and the 20-year-old said she had been in an incredible groove, carding her career-low round on the LPGA Tour.
"It was almost just auto-command kind of golf. I feel like in the last couple weeks it's been a little bit difficult. I've been struggling a little bit with the golf swing and gaining confidence in my preparation," she said.
"But going into this week I kind of let it all go -- let the expectations go a little bit more. I was able to free myself up a little bit, which was really nice to see some shots go in, especially on the greens. I was able to get some putting momentum in, so it was really nice," she said.
Zhang's only win on the LPGA came in New Jersey, where she won the Mizuho Americas Open in Jersey City in her first LPGA start as a professional last June.
Sweden's Madelene Sagstrom was two shots back of Zhang after her seven-under 65, recovering from a bogey on the third and making eagle on the par-5 12th.
South Korea's An Na-rin, Ireland's Leona Maguire and Australian Stephanie Kyriacou were all three shots behind Zhang after posting rounds of 66.