Diaz followed an opening-round 66 with a bogey-free 69 to finish the second day of the Corning Classic at 9-under-par. She is tied for the lead with Jean Bartholomew.
Bartholomew, born in Queens, N.Y., and now a resident of Garden City, had a terrific day recording three birdies on the front side as well as an eagle on the par-5 fifth. She carded nine straight pars on the way in to finish with a bogey-free 67 for the day and in great position for the weekend.
The 35-year-old joined the LPGA Tour in 1996. Her career best finish is a tie for second in the 2000 First Union Betsy King Classic.
Bartholomew almost didnt play this week. I wasnt really playing very good the last few weeks and I went home and worked on some things and changed my mind,' she said.
'Now here I am - in the lead after two rounds.'
Rookie Beth Bauer recorded five birdies on the front nine and a bogey on the par-4 16th, finishing the day tied with Jung Yeon Lee (69) for second place at 8-under, while first-round leaders Sherri Steinhauer and Beth Bader struggled.
Steinhauer shot even-par 72 to finish three back at minus 6. Bader, who started her round with a bogey on the 10th, seemed to get things in control for a while before stumbling over three consecutive bogeys on the par-4 finishing holes.
The second year tour member made the turn to the front side and continued her bogey jag falling to 3-over through her 10th hole of the day. She went on to shoot 77 and is now eight off the pace.
Full-field scores from the Corning Classic