Harris English is among four tied for the lead at the Northern Trust, while Tiger Woods made a solid start on Thursday.
English, Kevin Streelman, Cameron Davis and Russell Henley carded seven-under 64s in the first round at TPC Boston.
The quartet hold a one-stroke lead after their fine starts at the opening event of the FedEx Cup play-offs.
The leaderboard is congested, with Woods' three-under 68 only enough to be tied for 30th.
The 15-time major champion started on the back nine and was even through 11 before making birdies on four of six holes.
As he looked set to finish with a 67, Woods bogeyed his final hole, while Justin Thomas and defending champion Patrick Reed also managed 68s.
There are seven players tied for fifth at six under, with Louis Oosthuizen, Charley Hoffman, Scott Piercy, Bubba Watson, Kevin Kisner, Sebastian Munoz and Matthew Wolff shooting 65s.
Watson, who has missed six cuts in 14 events this year, carded seven birdies and a bogey to make a strong start.
Two-time Northern Trust winner Dustin Johnson opened with a four-under 67 to be in a tie for 20th.
The US PGA Championship runner-up was five under through 13 holes before producing two bogeys either side of his birdie at the sixth.
Rickie Fowler, who has struggled this year, also started with a 67.
Hoping to kick-start his year, Rory McIlroy carded a two-under 69 to be in a group tied for 53rd, alongside the likes of Jordan Spieth, Justin Rose and Jon Rahm.
In action for the first time since winning the US PGA, Collin Morikawa battled to an even-par 71.