Iwai, the 23-year-old Japanese player who won the Portland Classic in August for her first LPGA Tour title, shot a one-under 71 in the difficult afternoon conditions to get to 13-under 203.
“No change. Just keep going,” Iwai said. “Have smile and have fun.”
Second-round leader Youmin Hwang followed her career-best 62 on Thursday with a 75 on Friday to drop into a tie for second with Minami Katsu (66), Hyo Joo Kim (66), Megan Khang (67), Peiyun Chien (68), Brooke Matthews (69), Pornanong Phatlum (69) and Jessica Porvasnik (72).
“I’m sure there will be a lot of wind tomorrow, too,” Katsu said. “Hopefully, just try to be patient.”
The second-ranked Korda birdied the 18th for a 69 to get to 11 under.
Coming off a seven-victory season, Korda hasn’t won this year and lost her No.1 ranking to Jeeno Thitikul. The tour has had a different winner in all 24 of its official tournaments this year.
“For me the most important thing is giving 100 per cent to every shot.” Korda said. “That’s what I’m going to do tomorrow. You never know. Golf is a crazy sport. Sports are crazy.”
Nasa Hataoka also was 11 under after a 71. Defending champion A Lim Kim shot a 66 to get to 10 under.
Iwai steadied herself after a bogey on the par-3 12th, making a sensational up-and-down on No.13 for the first of six straight pars. She missed a chance to double the lead on the par-5 18th, blasting out of a bunker to six feet and failing to get the birdie try to fall.
On the par-4 13th, Iwai avoided a second straight bogey after hitting into a massive fairway bunker and leaving her approach 56 yards short in the right rough. She hit a wedge to three feet to start the par run.
Iwai shot a 64 on Wednesday to take the first-round lead, then had a 68 on Thursday to fall three strokes behind Hwang, the Korean LPGA star playing on a sponsor invitation.
Australian Gabriela Ruffels followed her rounds of 65 and 69 with a 75 on Friday.
The 25-year-old is now at seven under, six behind Iwai and tied 21st.
Ruffels began her round bogey-bogey and then started the second nine in similar fashion. She had another bogey on the 17th, but fought back with a birdie on the last to go with her other birdie on the third.
Compatriots Cassey Porter (69-74-69) and Robyn Choi (71-72-69) are three behind Ruffels, while Perth’s Hira Naveed (72-70-72) is at two under.
After the event, the LPGA heads to Asia for tournaments in Shanghai, South Korea, Malaysia and Japan.
