Rory McIlroy admitted a week of distractions had taken their toll after he suffered a nightmare start to The Barclays.
The world number one came into the first leg of the four-tournament FedEx Cup play-offs as a hot favourite following victories at the Open Championship, WGC-Bridgestone Invitational and US PGA Championship, but starting on the back nine at the Ridgewood Country Club, he made the turn in four-over 40 before picking up a shot on the way back
His round of 74 left him eight shots off the lead held jointly by six players who had reached the clubhouse - Cameron Tringale, Hunter Mahan, Charles Howell, Brendan De Jonge, Ben Martin and Brendan Todd.
McIlroy was within an inch or so of a birdie on the first hole he played, the 10th, but his form then deserted him as he registered a double-bogey on the 12th, his third hole, and followed that with bogeys on the 13th and 18th to leave him last of all players on the course at the time.
He pulled a shot back on the par-four fifth but gave it back on the eighth, missing a four-foot putt to bogey.
He recovered to birdie the ninth, his final hole of the day, finishing with a three-over round of 74 and at least off the very bottom of the leaderboard.
McIlroy, who appeared on late-night US television with Tiger Woods earlier this week, days after parading his Claret Jug at Manchester United's Old Trafford ground last weekend, said he needed to regain his focus to get back into contention.
"I'm not quite on my game, I've not quite put in the time over the last few days for obvious reasons," he said on Sky Sports.
"I'm going to go and have some lunch and then work on the range, work on a few things, and try to catch up on some practice I've missed out on over the last week and try to be ready for tomorrow."
Looking forward to the FedEx Cup, he added: "For me, not being here for the weekend isn't an option. I've got to work hard today on the range and get out there and get off to a fast start tomorrow, and get myself back into this tournament."
Justin Rose carded 68, dropping shots on the 12th and 17th to miss out on a share of the lead.
"My game feels close," he said on Sky Sports. "I played really well at the PGA as well but my putter let me down so I was really pleased today that there were some four, five putts that I got and that kept my momentum going. It was something I struggled with at the PGA.
"My ball striking was there or thereabouts. I didn't hit that many fairways today so I was happy to get round."
The top 125 players in the standings have qualified for The Barclays, with the field being trimmed to 100 for the Deutsche Bank Championship, 70 for the BMW Championship and then 30 for the Tour Championship with the man finishing top of the standings claiming a $10million.
McIlroy led the FedEx Cup standings coming into the tournament followed by Jimmy Walker, Watson, Matt Kuchar and Jim Furyk