'Wow, it was a struggle today,' said Garrigus. 'The swing was there but I was as nervous as I've ever been.'
Rick Price posted a 69 to finish alone in second place at 11-under-par 205 while Darron Stiles followed at 10-under-par 206. Jimmy Walker, Dave Stockton, Jr., and Scott Gutschewski were eight shots off the pace at 9-under-par 207.
Garrigus used rounds of 66 and 65 to carry a two-stroke lead over Walker heading into the weekend at Le Triomphe.
On Saturday, Garrigus picked up his first birdie of the day at the par-4 second and collected a birdie at the par-5 fifth to make the turn at 15 under.
The 26-year-old stumbled to a bogey at the par-5 12th but countered with a birdie at the 13th.
Garrigus, whose best finish on the Nationwide Tour was a tie for 25th at the Dayton Open in 2002, closed in style with birdies on each of his last two holes to extend his advantage with one round to play.
'We've still got one day of golf left so I need to stay calm and relaxed,' Garrigus said. 'I don't think I'll sleep a whole lot tonight. But with a six-stroke lead I think I have the advantage.'
Price, who is also looking for a breakthrough win, mixed two birdies and a bogey over his first nine holes.
The 35-year-old moved to 11 under with a pair of birdies starting at the 10th but faltered with a bogey at the 16th.
Price responded with a birdie at the 17th to finish six shots off the pace.
'If it is my day then it will be my day,' said Price.
Todd Demsey, Charley Hoffman, Justin Bolli, Charles Warren, Mike Springer and Brad Ott tied for seventh place at 8-under-par 208.
D.J. Trahan, Jon Mills and Mike Heinen were one shot further back at 7- under-par 209.