Rickie Fowler opened with a 65 in his first tournament since the PGA Championship, and at times it felt like he was getting lapped playing alongside Woods.
McIlroy picked himself up quickly from a double bogey on the par-3 eighth hole with a 3-wood onto a green so soft on the par-5 ninth that it barely bounced forward and caught a slope down toward the pin, leaving him a short eagle putt.
The plan was for another leisurely late-morning start due to the small field, but players were on the tee bright and early due to projected storms in the afternoon.
Woods was joined in the lead by McIlroy who highlighted his round of 10 birdies with a career-best six in succession, beginning with the last hole of his front nine.
Hideki Matsuyama shot a 6-under 64 to land three shots off the pace in a four-way tie for third.
Woods and McIlroy had played a nine-hole practice round together on Tuesday.
Japan's Hideto Tanihara shot a four-under 66 to lead by two strokes from Matthew Fitzpatrick, Dane Lucas Bjerregaard and Doug Ghim on nine-under par.
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It was an ugly first half for the Birds as they went into the locker room down 6-3. Atlanta's drive resulted in a punt, when they should have been in the red zone.
Woods and McIlroy still had to hit the shots and make the putts.
Leishman is projected to need at least a tie for 38th to remain inside the FedEx standings's top 30, who advance to the Tour Championship finale. Rickie Fowler had a nice round of his own right alongside Tiger and Rory McIlroy (who's now on 59 watch) and Billy Horschel, both past FedEx Cup champions, caught fire at Aronimink as well.
Schauffele also needs a good week to get to Tour Championships at East Lake, and his goal would be to extend his season an additional week in France at the Ryder Cup.
Schauffele, the victor of last year's Tour Championship, had been among the frontrunners for a Ryder Cup spot with strong performances at the U.S. Open (equal sixth) and British Open (equal second). I didn't want to lose too much ground.
And while DeChambeau admits to being a "little tired", he is eager to take on the Aronimink Golf Club course which played host to the 1962 PGA Championship and more-recently the PGA Tour's 2010 and 2011 AT & T National.
"This was the shot of the entire day, a three-iron from 230 and I just laced it up in the air", the 42-year-old American said. "But they didn't go in today".
Finau finished solo second at the Northern Trust and T-4 at last week's Dell Technologies Championship.