World No. 1 Jordan Spieth declared his Barclays Championship opening four over par 76 to be the "worst round I’ve played in years".

The double major winning Texan was two under par through six holes but then completed his inward nine in six over par with Spieth posting one birdie but also six bogeys and a 12th-hole double bogey on the Plainfield Country Club course in Edison, New Jersey

It left Spieth trailing 10 shots behind fellow Masters champion Bubba Watson in the first of the four FedEx Cup Play-Off events.

“I would argue that this was, after the tee shots, this is the worst round I have played in years, for hitting so few fairways," said Spieth. “I’ll just take it at that, that it’s just a fluke. I made some birdies, like only three, but typically I should make more than that. So it was a very off day with a little bit of rust with the wedges and combined some poor decision making and it just came out of nowhere.

Meanwhile, the PGA Tour Commissioner, Tim Finchem has afforded Rory McIlroy a special ‘concession’ to retain full 2015/16 Tour membership given McIlroy will not contest the minimum 15 events.

McIlroy has played just nine events and while missing from this week’s Tour stop in New Jersey, he will end the year looking likely to contest 12 but he has been granted the concession because he had originally informed the PGA that he would compete in 15 events before his infamous knee injury ruled him out.

The Scotland pair of Russell Knox and Martin Laird were out in the afternoon half of the $US 8.25m event.