Hossler started his second round with a three-putt bogey from about 30 feet, and felt like he made just about everything after that, including a 30-foot eagle putt on the par-5 fifth hole.
Daniel Berger, out of golf for 18 months with a back injury, had another round of seven birdies and no bogeys for a 65 and was one shot behind.
The group two back included Keith Mitchell (64), Jacob Bridgeman (66) and Englishman David Skinns, who opened with a course-record 60 and had to rally with three birdies on the back nine just to break par with a 71.
Hossler was at 15-under 129 on the soft, still and vulnerable Country Club of Jackson. The cut was at six-under 138.
"If you go out and try and shoot eight-minus, nine-under par, it's not going to happen," Hossler said.
"You've got to try and take it one at a time, try and pick apart the par 5s as best you can, birdie the drivable hole. And there you are already starting three minus, four minus, five-under par."
He nearly followed that script, except for missing a 12-foot birdie on the par-5 13th. But he played the par 5s in four under with the eagle, and made short work of the short par-4 15th.
Berger was No.25 in the world when he stepped away with back trouble after the 2022 US Open at Brookline. He was at No.664 when he felt good enough to return in January at The American Express. Only recently has he felt closer to normal.
"I think it's kind of a process," he said. "You're working every day to get one per cent better, and then you got to a point where you don't have to think about it or worry about it and that's kind of where I am now."
The FedEx Cup Fall for most players is all about finishing in the top 125 in November to secure a full card for 2025. Bridgeman took a big step. He came into this week at No.123, and now can think about a far bigger prize.
Skinns lost a little ground as expected. He had a three-shot lead on Thursday but 24 hours later he already was five shots behind Hossler when he teed off for the second round.
Skinns made a pair of bogeys and was sliding down the leaderboard until pulling it together on the back nine to go into the weekend just two shots back.
Former US Open champion Gary Woodland, who is taking it slowly from brain surgery just over a year ago, posted a bogey-free 68 that left him in the group three behind at 12-under 132.
Aaron Baddeley, the lone Australian in the field, missed the cut after rounds of 73 and 77 for a six-over total.Â
