Woods then capped a strong display by nailing a 27-foot eagle putt to be five under alongside fellow American Rickie Fowler.
This felt even better on a dry, tougher East Lake course.
It is heady territory for Woods after his spinal fusion a year ago, making his first appearance in the tour's season-ending championship since 2013.
World No. 1 Justin Rose is but a one back at 4 under, with No. 4 Justin Thomas and No. 5 Rory McIlroy just two back, shooting 3-under 67s.
While there is a lot of golf yet to be played this week, the leaderboard shows Woods projected to finish second in the FedEx Cup if all players were to maintain their current positions in the field. I don't know if we'll get that this week, but I'm excited to watch McIlroy, who ranked in the top five in the field in approach shots on Thursday, try to snag a FedEx Cup from the No. 17 slot in the field.
"I don't know who it was", he said. In fact this first round was a vast improvement over the 73 he posted on Thursday in 2013, his last appearance at East Lake.
Impact Of Alzheimer's Disease Will Double By 2060 — CDC Report
Alzheimer's disease progresses to dementia, which is a degeneration of the brain and worsens over time, eventually proving fatal. Experts worry people are being put off seeing a doctor because they're so anxious about how their life will change.
But in good health and seemingly feeling great about his game, in advance of next week's Ryder Cup event, Woods certainly has a better-than-average chance at winning this weekend's prestigious tournament.
Woods implored himself to hole more putts with forecasted Friday night storms expected to further soften conditions at Aronimink.
Fowler matched Woods, posting his fourth 65 in his past five rounds, while Rose shot 66 despite wedge play he described as "so bad" in a conversation with his caddie picked up by the on-course microphone. The tournament's co-leaders, Woods and Fowler, would be five and six shots back, respectively.
"I told Thomas, "if you end up picking me, I'll make sure that I play something coming into the Ryder Cup", Garcia said on Wednesday, ahead of the tournament at the Algarve resort of Vilamoura.
There were 10 players in the 30-player field who shot over par in the first round, including BMW Championship victor Keegan Bradley and Phil Mickelson, a captain's pick for the U.S. Ryder Cup team next week.
Bryson DeChambeau, the No. 1 seed after the points were reset, had to birdie two of the last three holes for a 71. Houses along the side streets outside East Lake, and even one funeral home, offered parking and their yards were packed. "But I thought I could sneak it up there and get up on the upslope and have a good angle in there, and it just didn't work out".