A birdie at his final hole allowed Koepka to establish an important break heading into the weekend after struggling through much of his closing nine holes.
An approach from 240 yards set up a two-putt birdie from 10 feet and the world number one is on track to win not only his first Tour Championship but the huge $15 million bonus for taking out the FedEx Cup.
Koepka was always one to keep in perspective the new format of the event and was again asked about his thoughts after his round.
“Yeah, everybody makes a big deal about it,” said Koepka. “But most of the time when we tee off on Thursday, we're already six, seven behind because the morning wave is done. It's not a big deal. You just go out there and try to close that gap, and I've done a good job with that.”
Xander Schaffele is in 5th place on his own at 11 under and two from the lead with Paul Casey at 9 under in 5th place alone.
Adam Scott trod water on day two, a round of even par 70 having him in 10th place and eight shots from Koepka.
Marc Leishman continued his recent indifferent form and is in 28th place in the 30 player field.
Want video tips delivered straight to your inbox? Subscribe to iseekgolf.com newsletters.