The round was suspended for darkness with several players still on the course. They will return to the Crenshaw Cliffside Course at Barton Creek Resort at 8:00 a.m. ET Saturday to complete the second round.
Rob McMillan posted his second consecutive 4-under 66 on Friday and is alone in second at 8-under-par 132. Brian Guetz carded a 3-under 67 and has sole possession of third place at minus-7.
Gillespie wasted little time in breaking into red figures as he birdied his first two holes of the second round. He extended his lead to seven with a birdie at 16, but things fell apart.
He three-putted for bogey at 17, then made a 5-footer to save par at the 18th. Gillespie then ran off four consecutive bogeys to bring everyone back into the mix.
McMillan birdied his last hole to draw even with Gillespie at minus-8. Gillespie pulled out an 8-iron at the eighth and knocked his tee ball 4 feet past the hole. His ball spun back and into the hole for an ace and a two-shot lead.
'I lost it in the shadows and didn't even see it go in,' admitted Gillespie, a two-time winner on the Canadian Tour. 'It could not have come at a better time.
'I lost my focus out there for a while. To go from 13 under to 8 under in a hurry can throw you off and I was second-guessing myself. I just wasn't in the game and it felt like I was beating myself up to get through the day. I'm still right where I want to be, so I'll try to get it turned around.'
Stephen Gangluff (67), Alan McLean (66) and Ben Bunny (69) are tied for fourth place at 6-under-par 134. Peter Tomasulo fired a 5-under 65 and shares seventh with Chris Baryla, who is at 5 under par through 14 holes.
Dave Levesque (67), Matt Bettencourt (72) and Omar Uresti (73) are knotted in ninth at 4-under-par 136. Brian Flugstad is 4 under par through 11 holes.