Bryce Molder was able to maintain his one-shot lead as weather in Fort Worth wreaked havoc during the second round of the Dean & DeLuca Invitational.
Play was delayed for over five-and-a-half hours at the start of Friday's round, with Molder only able to tee off in the evening in Texas.
The disruption in play meant Molder was through 15 holes when darkness suspended the second round at Colonial Country Club, with Webb Simpson and world number two Jordan Spieth looming.
Molder's time spent on the course was impressive, having posted five birdies in a flawless front nine to be three under with three holes remaining in his second round.
Simpson was able to complete his round to be eight under after 36 holes.
The American was almost bogey-free, only dropping one shot at the seventh for a three-under-par 67.
Two-time major winner Spieth is within touching distance, only a stroke further back in the leaderboard.
The out-of-form 22-year-old has not won since January's Tournament of Champions, while he suffered dramatic collapses at the Masters and AT&T Byron Nelson.
But Spieth is only two shots off the pace thanks to his second-round 66, alongside Patrick Reed, who was through eight holes on Friday.
Tied for fifth at six under are Anirban Lahiri (through 12) and Jason Dufner (through 10).
Defending champion Chris Kirk is above the projected cut line at even par with nine holes remaining in his second round.
Meanwhile, 2014 winner Adam Scott is set to miss the cut, with the Australian two over the card after nine holes.