Embarrassingly, the World No. 1 found himself near the tail of the field at the start to the four-tournament FedEx Cup Play-Off Series at the Ridgewood Country Club course at Paramus.
McIlroy trailed seven shots behind the clubhouse leading trio of Americans Charles Howell III, Cameron Tringale and Hunter Mahan who signed for five-under-par 66s.
Eleven days ago, McIlroy won a second PGA Championship to make it three wins in succession, but after this first round, he’s about as far away as New Jersey is from Kentucky in achieving four wins on the trot.
McIlroy is now staring at the prospect of ending his PGA Tour season should he miss the Barclays halfway cut.
While McIlroy topped the FedEx Cup qualifying points table, all 125 players started from scratch this week. McIlroy needs to be in the top 120 if he is progress to Boston next week.
Then it will mean completing the Deutsche Bank Championship inside the top 70 to qualify for the penultimate Play-Off Series event, the BMW Championship in Denver.
And to be eligible for the season-ending Tour Championship and have any chance of capturing the FedEx Cup and the bonus purse of $10m, McIlroy will need to finish top 30 in Colorado.
This was McIlroy’s poorest round since the ‘Friday Fright’ of day two 78 in last month’s Scottish Open.
And McIlroy ruled out any suggestions of fatigue in the wake of his ‘Triple Crown’ winning effort in capturing The Open Championship, the WGC Bridgestone Invitational and last fortnight’s fourth Major triumph, in capturing a second PGA Championship.
Straight after being handed a second Rodman Wanamaker trophy, he spent three days celebrating in nearby New York before crossing to Manchester to be guest of honour at last Saturday’s Premier League opener at Old Trafford then jetting back to the Big Apple for corporate work, TV appearances and an Ice Bucket Challenge with Tiger Woods and TV star Meghan Markle.
His only look at the course was a three-hour practice session on Monday and then a five-hole Pro-Am on the eve of the $8m event.
“Fatigue isn’t playing a part. It’s just not putting in time in that I probably should have over the past week and I allowed myself that and I deserved that,” said McIlroy.
“So I need to work hard on the range this afternoon and go out tomorrow and shoot a number.”
After a short lunch break, McIlroy headed for the practice range with his first round stats showing he hit just half of the 14 Ridgewood fairways, a dozen of 18 greens in regulation and recorded a total of 32 putts.
Graeme McDowell, the only other Irish golfer in the field, was out in the afternoon half of the draw.