Lewis, who was the outright leader in the first two rounds, survived a double-bogey on the 15th hole to finish at 1-over 73 for the round and an 11-under 205 for the LPGA tournament.
Saturday's 73 was 10 strokes over the 63 she fired in Thursday's opening round. She was 2-under on Saturday before hitting a rough patch that included bogeys on the 12th and 14th holes and a double-bogey on 15. Her birdie on 18 kept her from slipping into second.
Park was 2-under Saturday. She also had two bogeys on the back nine and birdie on 18.