Rory McIlroy is five off the lead after carding a two-under-par 69 on the opening day of the Northern Trust, the first of the PGA Tour's three FedEx Cup play-off events.
Only the top 30 after that advance to the Tour Championship in Atlanta, which McIlroy won for the second time in four years in 2019 to claim the overall FedEx Cup title and pocket the $15m first prize.
McIlroy got off to a slow start with dropped shots on the 12th and 13th, but birdied the 15th, 16th and 18th to reach the turn in 34. Two more birdies and one bogey on the front nine saw the former world number one sign for a 69.
Shane Lowry is three behind McIlroy on one-over while Graeme McDowell props up the leadrboard on six-over following his difficult 77.
At the top, American Harris English shot a 64 to leave him on seven-under and he was joined by compatriots Kevin Streelman, Russell Henley and Australia's Cameron Davis.
Meanwhile Tiger Woods recovered from a sluggish start to card a three-under-par 68.
Starting on the more difficult back nine at TPC Boston, Woods played his first eight holes in one over par before a birdie on the 18th took the 15-time major winner to the turn in level par.
The front nine offers more birdie opportunities and Woods took advantage by picking up shots on the third, fourth, seventh and eighth before a wayward drive led to a disappointing bogey on the ninth.
At three under par Woods was four shots off the pace set by a quartet that shared the lead at the end of the first round.
Woods used a slightly different putter on his way to a tie for 37th in the US PGA Championship but reverted to his old favourite on Thursday.
"I had a good feel today," the 44-year-old said. "I had nice pace and I like the speed of these greens. They're fast. Even though they're soft, they're still quick.
"I just felt comfortable. That's one of the weird things about golf. It's just the way it is sometimes."
Woods began the week at 49th in the FedEx Cup standings, with the top 70 on Sunday evening qualifying for the second event, the BMW Championship in Chicago.
England's Tommy Fleetwood was left to rue a disastrous end to his round.
The 29-year-old had a share of the lead headed into the final two holes, but a bogey at the 17th and a double bogey on the 18th forced him to finish two shots off the lead with a five-under 66.
Joining him at equal-12th on the leaderboard is fellow Briton Ian Poulter.
Poulter, who has yet to qualify for the Tour Championship at East Lake, carded six birdies and one bogey in his 66 as he looks to move up from 85th in the standings.
"I really haven't done any good in the play-offs before, so I've never made it to East Lake. It's a myth apparently to me," Poulter said.
"Apparently it's a nice golf course, but what would I know? I've never been there.
"I think what's important to me is that I just go out and enjoy my golf and play well. If I play well and I move up, that's great, and if not, I really don't care, I'm going to go home to the family. Whatever happens this week is a win-win."
