"I've played it (Crosswater) two times this year and have had no bogeys," said Sullivan, the PGA director of golf at Hanging Rock in Salem, Va. "I've just figured out a way to play the course. Some holes I can be aggressive and some I can't."
Second-round leader Rod Perry was a stroke back after a 73. The 39-year-old Perry, the PGA head pro at Crane Lakes in Port Orange, Fla., played the first six holes in 4 over.
"I really struggled out of the gate today," Perry said. "I made a few birdies to bounce back a bit. But I am not out of it. I have a chance tomorrow. Chip and Mark are both playing extremely well and are going to be tough competitors tomorrow."
Ryan Polzin shot a 70, matching the best round of the day, to reach 6 under. The 33-year-old Polzin is the PGA head pro at Royal Oaks in Houston.
The top 20 finishers Wednesday will earn spots in the PGA Championship in August at Oak Hill in Rochester, N.Y.