Hossler's bid for a sub-60 score on Friday was denied when he had pars on the final three holes at a water-logged Sedgefield Country Club.
"Probably the highlight of the round was just mid-irons," Hossler said. "A few six irons I hit really close, five iron I almost made a hole-in-one. It was one of those days where it felt like kind of everything went right."
Hossler holds a two-stroke lead on Billy Horschel, who is at eight under with two holes still to finish Saturday to complete his first round.
The opening-round was moved to Friday because of rain and then postponed by darkness with a number of competitors still on the course.
Canada's Nick Taylor, through 14 holes, is at seven under and alone in third place. Taylor had birdies on four of his last five holes before play was halted.
Heavy rains and local flooding stemmed from remnants of Hurricane Debby. Friday's start was pushed back three hours as course maintenance crews worked to get the grounds ready for play.
Several dozen golfers will need to finish the first round Saturday and then go directly into the second round.
Cam Davis was one of the finishers, making a one-under 69 to be the leading Australian.
On his return from Paris at the Olympics, compatriot Min Woo Lee is even par through 16 holes while Aaron Baddeley closed with a one-over 71.
Hossler played the first eight holes in seven under, boosted by a tap-in eagle on the par-5 fifth hole. He posted a personal-best 28 on the front side.
He birdied No.10 and was on pace for an epic round before a bogey five at No.11. A birdie followed at No.12, needing only about a one-foot putt after his tee shot on the par-3 hole, put him right back on track.
Hossler's tee shot at No.18 was in the left rough, reducing his chances of a birdie.
"There was just no way I'd be able to get it on that shelf to have a real look," he said.
Hossler, 29, has never won in 197 previous events since joining the PGA Tour in 2018.
Matt Kuchar, Brendon Todd, Austin Eckroat and England's Ben Taylor, all playing in the group in front of Hossler, finished at six-under 64 to tie for fourth.
The tournament is the final stop on the PGA Tour's regular season. It's the last chance for golfers to move into the top 70 spots to qualify for the FedExCup playoffs, which begin next week.
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