Charley Hoffman was still top of the leaderboard when the second round of the Houston Open was suspended due to darkness, as Jordan Spieth struggled.
Hoffman carded a two-under-par 70 to maintain his one-stroke lead at the Golf Club of Houston on Friday, despite bogeying the final hole.
With most of the field gearing up for next week's Masters at August, overnight leader Hoffman did not do too much wrong, going bogey free on the front nine, which featured back-to-back birdies at the third and fourth holes.
The three-time PGA Tour champion dropped the 13th and 18th holes after the turn, but had two birdies in between to stay clear of countryman Jamie Lovemark (68) at 10 under.
Fellow Americans Chez Reavie (68) and Dustin Johnson (71) are a stroke further back.
Roberto Castro and Jamie Donaldson are also eight under through 36 holes but they were two of 28 players still out on course when played was cut short, with those rounds to resume on Saturday.
Last year's runner-up Spieth did complete his 18 holes but it was a mostly forgettable day for the reigning Masters champion.
Spieth endured a mixed day from tee to green, only hitting eight of 18 greens in regulation and posting three birdies to go with four bogeys as he shot a second-round 73.
The world number two is now 10 shots off the pace heading into the weekend, having teed off just three strokes behind Hoffman.
"I've got to putt better," Spieth said. "I'm losing a couple strokes back to the field on the putting, and normally we're gaining strokes.
"Inside 10 feet, I've got to be solid and confident, but I can't get into a rhythm."