Justin Rose carded a six-under 65 to take the lead after the first round of the Dell Technologies Championship.
The Englishman handled windy conditions to hit a bogey-free round at Boston TPC - one of only two players to do so.
His lead is small, however, with Abraham Ancer and Scotland’s Russell Knox hot on his heels just one shot behind on five-under.
Rory McIlroy finished with a flourish to leave himself six shots off the leader in Boston, with a birdie at the 18th – thanks to an excellent bunker shot – completing a level par round of 71 on a difficult scoring day.
For Tiger Woods it was more of a grind on the opening Friday (the tournament finishes on Monday as it is Labour Day in the US) but he limited the damage to keep himself well in the tournament at one over par.
McIlroy – playing in his first FedEx Cup playoff event of the season after he skipped last week’s Northern Trust – was coasting along nicely on the tough layout with a birdie at the fourth moving him to one under.
However, a bad patch on the back nine saw him drop shots at the 13th and 15th to slip to one over par.
But McIlroy, who said on Thursday that he has been working on a new swing change after a week of intense work with his coach Michael Bannon, flipped a lovely sand shot out from a greenside bunker at the last before rolling in a putt for the birdie four to sign for a 71.
McIlroy came into this week at 28th in the FedEx Cup rankings but still well in contention to claim the title for the second time with two more playoff events to go after this weekend.
For Woods the round threatened to derail early after he was forced to convert a 10-foot putt just to save bogey at the 10th, his opening hole.
Further bogeys followed at the 13th and 16th before a first birdie of the day came along at the 17th.
From there Woods kicked on with another birdie at the fourth but dropped back again thanks to a five at the sixth. However, two huge hits at the 600-yard Par 5 seventh, his 16th, left him two putts for his birdie four before a par at the last completed a 73.
Four birdies on the back nine helped world number one Dustin Johnson to a round of 68 while FedEx Cup leader – and last week's winner – Bryson DeChambeau signed for a round of 70 and one under.
Woods currently sits 25th in the FedEx Cup standings, with the top 70 making it to next week’s BMW Championship and the top 30 ultimately qualifying for the season-ending Tour Championship.
Collated first round scores in the USPGA Dell Technologies Championship (Gbr & Irl unless stated, par 71):
65 Justin Rose
66 Abraham Ancer (Mex), Russell Knox
67 Keegan Bradley (USA), Chris Kirk (USA), Beau Hossler (USA), Gary Woodland (USA)
68 Xander Schauffele (USA), Brian Harman (USA), Adam Hadwin (Can), Webb Simpson (USA), Dustin Johnson (USA), Marc Leishman (Aus), James Hahn (USA), Rafael Cabrera-Bello (Spa)
69 Austin Cook (USA), Byeong-Hun An (Kor), Charles Howell III (USA), Tony Finau (USA), Peter Uihlein (USA), Tommy Fleetwood, Kevin Kisner (USA), Jordan Spieth (USA), Henrik Stenson (Swe), Alex Noren (Swe), Kevin Chappell (USA), Brooks Koepka (USA), Cameron Smith (Aus), J.B. Holmes (USA), Tyrrell Hatton, Cheng-Tsung Pan (Tai), Paul Casey
70 Andrew Putnam (USA), Kyle Stanley (USA), Branden Grace (Rsa), Si Woo Kim (Kor), Kevin Na (USA), Danny Lee (Nzl), Bryson DeChambeau (USA), Jimmy Walker (USA), Brice Garnett (USA)
71 Hideki Matsuyama (Jpn), Pat Perez (USA), Adam Scott (Aus), Aaron Wise (USA), Scott Piercy (USA), Louis Oosthuizen (Rsa), Matt Kuchar (USA), Jamie Lovemark (USA), Rory McIlroy, Russell Henley (USA), Ryan Armour (USA), Kevin Tway (USA), Jhonattan Vegas (Ven), Patrick Reed (USA), Ryan Moore (USA)
72 Brian Stuard (USA), Nick Watney (USA), Jason Kokrak (USA), Tiger Woods (USA), Brian Gay (USA), Bubba Watson (USA), Stewart Cink (USA), Phil Mickelson (USA), Brendan Steele (USA), Emiliano Grillo (Arg), Whee Kim (Kor), Michael Kim (USA), Brandt Snedeker (USA)
73 Charley Hoffman (USA), Scott Stallings (USA), Zach Johnson (USA), Andrew Landry (USA), Ryan Palmer (USA), Patrick Cantlay (USA), Tom Hoge (USA), Chez Reavie (USA), Daniel Berger (USA), Justin Thomas (USA), Jon Rahm (Spa), Ian Poulter, Keith Mitchell (USA)
74 Ted Potter, Jr. (USA), Patton Kizzire (USA), J.J. Spaun (USA), Troy Merritt (USA), Anirban Lahiri (Ind), Bronson Burgoon (USA)
76 Luke List (USA), Satoshi Kodaira (Jpn), Jason Day (Aus), Kelly Kraft (USA)
77 Joel Dahmen (USA), Ollie Schniederjans (USA)
78 Kevin Streelman (USA)
79 Chesson Hadley (USA)
80 Jason Dufner (USA)
