Massachusetts - British Open champion Phil Mickelson flirted with a 59, but settled for an eight-under-par 63 and a share of the first-round lead on Friday alongside England's Brian Davis.
Mickelson had eight birdies and an eagle along with two bogeys to set the early pace, and Davis joined him atop the leaderboard with a blemish-free round that featured eight birdies.
They were one stroke in front of American Kevin Stadler, with Spain's Sergio Garcia, and Americans Hunter Mahan and Roberto Castro a further shot back on 65.
A group of 16 players on five-under 66 included England's Lee Westwood and Ian Poulter, South African Ernie Els, Sweden's Jonas Blixt and 2009 British Open champion Stewart Cink of the United States.
Mickelson was the class of the morning, teeing off on the 10th hole at TPC Boston alongside world number one Tiger Woods and Masters champion Adam Scott.
He birdied seven of his first nine holes. A bogey from a bunker at the first was followed by an eagle three at the par-five second, where his second shot landed two feet from the pin. He nabbed another birdie at the par-three eighth, but closed with a bogey when he hit his tee shot at the ninth into thick brush on the right.
The tee shot on nine and his wedge at the first were the "only two bad swings" of his day, Mickelson said.
Woods, who battled back pain in a runner-up finish to Scott at The Barclays last week, carded a three-under-par 68 that included four birdies and a bogey.
He said his back was "all good" especially after an extra day off because of the $8 million tournament's Friday start. The event, the second of four in the US PGA Tour's season-ending playoffs, will conclude on Monday, the US Labor Day holiday.
"It helped having that extra day off," Woods said. "It made a difference.
"I didn't hit the ball as well as I'd like to, but I scored all right," he added. "I didn't give myself a lot of looks."
Things were even more of a struggle for the third man in the group, as Scott battled to a two-over 73.
The Aussie, who moved to number two in the world with his win last week at Liberty National, went two-over with bogeys at the 10th and 14th, picked up his only birdie of the day at the par-three 16th, then gave the shot back with a bogey at the par-four sixth.
Defending champion Rory McIlroy, trying to turn around a disappointing season carded a one-under 70 that he called "sloppy".
"I'm making a lot of birdies, but also making a lot of stupid little mistakes," said McIlroy, who is without a win in 2013. "If I can cut those out, it's a different story."
Leading first-round scores on Friday in the $8 million Deutsche Bank Championship, second event in the US PGA Tour playoffs (USA unless noted, par-71)
63 - Phil Mickelson, Brian Davis (ENG)
64 - Kevin Stadler
65 - Hunter Mahan, Sergio Garcia (ESP), Roberto Castro
66 - John Huh, Chris Kirk, Lee Westwood (ENG), Harris English, Jason Dufner, Nicholas Thompson, Stewart Cink, Bob Estes, Jerry Kelly, Ryan Moore, Jonas Blixt (SWE), Kevin Streelman, Steve Stricker, Matt Kuchar, Ian Poulter (ENG), Ernie Els (RSA)
67 - Brian Gay, Henrik Stenson (SWE), Graham DeLaet (CAN), Jordan Spieth, Boo Weekley, Robert Garrigus, KJ Choi (KOR), John Merrick, Jason Day (AUS), Charl Schwartzel (RSA), Brendan Steele