Jordan Spieth admitted he was “searching for answers” after the American missed the cut at The Barclays in New Jersey by five strokes.
The American shot a four-over-par 74 on the opening day and his struggles continued on Friday as the 22-year-old recorded five bogeys, a double-bogey and four birdies for a round of 73.
It is just the third time this season the two-time major champion has been on the wrong side of the cut line, with the other two coming in the Farmers Insurance Open and the Players Championship.
The result also means the 2014 Ryder Cup star will drop down to second in the world rankings after he failed to finish tied-14th or better to hold top spot.
The five-time PGA Tour winner only overhauled Rory McIlroy after clinching second at the US PGA Championship recently but the poor performance means the Northern Irishman will return to number one.
Spieth, who will be looking to bounce back in the second FedEx Cup event – the Deutsche Bank Championship, says he will go away and attempt to work out exactly what went wrong.
“I’m definitely searching for answers,” he told reporters. “I don’t know exactly what I’m going to do from here as far as how I get prepared for next week [the Deutsche Bank Championship] but I have some time to figure it out.
“I’ve reached that peak already and I know it’s going to be close enough to where if I just get the job done next week, I’ll be back in that ranking.”