American Chris Kirk took control of the McGladrey Classic on Friday while world number 19 Webb Simpson was among a pack of four golfers in the clubhouse one shot back before darkness halted second round action.
Kirk fired a second consecutive four-under 66 that gave him an eight-under 132 total on the Seaside layout at Sea Island, Georgia, where 18 players were still on the course when darkness halted proceedings for a second straight day.
A one-time winner on the PGA Tour and a former resident of the island, Kirk started his round four shots off the round one lead and stumbled with an opening-hole bogey but recovered nicely with five birdies over his next seven holes.
It was good enough to put the 28-year-old one clear of fellow Americans Simpson (68), Kevin Chappell (68) and Briny Baird (70) plus Australian John Senden (67).
Jason Kokrak (65), Ted Potter Jr. (67), Scott Brown (68) and Tim Clark (67) were a further shot off the pace at six-under while the best of those yet to finish was South Korean Noh Seung-yul, who was five-under with four holes to play.
While Kirk took top spot, the focus was heavily on former U.S. open winner Simpson, who is looking to add to his Las Vegas victory in his previous start three weeks ago.
Simpson, a four-time winner on the PGA Tour, held a share of the lead until a bogey on the penultimate hole, the par-three 17th, left him one back.
Having won in Las Vegas in his only other start in the new 2013-14 season, Simpson is looking to become the first player to win in back-to-back starts since world number one Tiger Woods won the World Golf Championships Cadillac Championship and Arnold Palmer Invitational earlier this year.
First round leader George McNeill, who finished off a career best 62 in the early hours of the morning, could not back up his efforts shooting a six-over 76 to drop to two-under.
World number eight Matt Kuchar, the highest ranked player in the field, is also in the mix after his second straight 68 left him just four off the pace.
Defending champion Tommy Gainey will not be going back-to-back, struggling to a 74 to be at four-over and well outside the projected cut.