Rory McIlroy showed he's human after all as he struggled to a three-over 74 in opening round of The Barclays at Ridgewood Country Club in New Jersey.

Leading the FedEx Cup point and keen to win the series and the $10m bonus, it was his first round over par since he shot 73 in the final round of the US Open in June, bringing to an end a run of eight straight rounds in the 60s.

"I just wasn't very good," McIlroy said after his round, admitting that taking a week off to celebrate his amazing run of victories was the reason he would end the day nine strokes behind leader Bo Van Pelt (65).

"Fatigue isn't playing a part," he told AP. "It's I think just not putting the time in that I probably should have over the past week. And I think I allowed myself that and deserved that. But this is the consequence of it and I need to work hard this afternoon and go out tomorrow and shoot a good number."

The world No 1, who is bidding for a four successive victory following wins in The Open, the WGC-Bridgestone Invitational and the US PGA, repaired some of the damage when he rolled home a 32 footer for birdie at the 440-yard ninth, his final hole.

But having become the third youngest player in the history of the game to win four majors, he reckoned he deserved a few days off to celebrate.

"I wanted to enjoy it for a week," he said.

As for his 74, he said: "It's not a bad thing. A score like this would be tougher to take if I had not just come off the weeks that I had. 

"But at the same time, I want to play well and I want to give myself chances to win tournaments.

"I'll need to get off to a good start tomorrow to try and do that. There's chances on this golf course to make birdies. I feel like I can do that."

It was still a surprising start to the week for the 25-year old, who struggled from the moment he short sided himself and double bogeyed the par-four 12th (his third hole) by taking four to get down from the right greenside trap. 

He then bogeyed the par-five 13th when he found sand off the tee and his third to go three over after four holes.

Forced to lay up after a pulled drive at the par-five 17th, he could only make par there and then bogeyed the 18th,  taking three to get down from 25 yards after missing the fairway right.

Out in 40, he came home in one under despite failing to birdie the par-five third, where he again missed the fairway.

He didn't make his first birdie of the day until his 14th hole — the 291-yard, driveable fifth — where he chipped to six feet.

But after saving par from eight feet at the seventh, he bogeyed the 217 yard eighth where he pulled his tee shot into the rough and then missed a four footer for par before picking up that birdie at the last.

His 74 left him nine strokes behind Van Pelt, who leads by one from Cameron Tringale, Hunter Mahan and Charles Howell III.

With just two weeks of the Ryder Cup campaign remaining for the Europeans and Graeme McDowell playing his last event before his wife gives birth to their daughter next week, there is much at stake for the Europeans.

McDowell holds down the last of nine automatic spots in the European team but by a slim margin from Luke Donald (71).

Lee Westwood, who needs a big week to force his way into the side or risk needing a wildcard, also shot 70 while Ian Poulter was disappointed with a 72 as he bids to pursuade Paul McGinley that he's worthy of a wildcard.

The nine automatic qualifiers for the US have already been decided but Mahan did his wildard hopes no harm with a 66.

"It will be a bonus to make it to Atlanta and it will be a bonus right now to make the Ryder Cup team," Mahan said. "So I have nothing to be nervous about or get out there and doubt myself. I have to trust myself because everything I'm doing is good and everything else will kind of take care of itself."