Defending champion Leona Maguire sits five strokes off the lead at the LPGA Drive On Championship but Stephanie Meadow currently heads the Irish challenge in Arizona.
Cavan native Maguire claimed her first win on the LPGA Tour at the tournament last year - the first Irish player to achieve that feat - when it was held in Florida.
This time at the Superstition Mountain golf club course, Maguire carded a 70 which leaves her on two under.
Starting on the back nine, Maguire birdied the 11th and moved up to two under with another on the second after embarking on the front nine.
A bogey on the fourth held her back briefly but a birdie on six quickly remedied that setback.
Meadow went two strokes better, posting a blemish free 68 to sit tied-16th and three off the lead. The Antrim woman carded birdies on 2, 7, 13 and 18 with no dropped strokes in her opening round.
A trio of players head the field on seven-under, Mexico's Gaby Lopez, Jenny Shin of South Korea and American Alison Lee, the latter on course to lead on her own prior to a closing bogey.
England's Jodi Ewart Shadoff is one stroke further back after a 66 on Thursday, joined by Wei-Ling Hsu.
