Atwal, who had two birdies in first five holes turned in even par. But then in a space of five holes he dropped four bogeys and a triple bogey eight on par-5 11th to card a six-over 42 for back nine.
Will Wilcox fired a course-record 63 Saturday and moved into a nearly insurmountable lead after 54 holes. Wilcox carded his personal best and it was also a tournament record as he moved to 16-under 200 total, seven strokes in front of his nearest competitors.
Wilcox destroyed the course on a day when only nine of 65 players posted sub-70 scores. His 63, which included a bogey at the final hole, and was five strokes better than the next best scores -- 68s by Spears and Will MacKenzie.
His seven-shot lead matches the second-biggest 54-hole advantage in Tour history.
Bhavik Patel (67-70-74) slipped to tied 12th after being second at the end of 36 holes.