Sharp has a one-shot lead over American Emma Jandel.
Sharp, who won this event in 2004, said winning this tournament would give her a huge boost for the rest of the year.
"It would be huge for me, I've been struggling all year,” said Sharp, a seven-year LPGA Tour veteran. "But today I was hitting it well and hoping to do it well again tomorrow to get on a consistent string.”
Sharp's best finish this year on the LPGA Tour was being tied for 25th in April at the Lotte Championship.
American Lisa Ferrero, another LPGA Tour member, is two shots off the pace while Lisa Maunu of St. Thomas, Ont., opened with a 1-under par, 72.