Rory McIlroy slipped to last place at the BMW Championship in Illinois after a six-over-par 77 in the second round.
The defending champion requires a top-eight finish to progress to next week Tour Championship but he lies 70th on 13 over and 24 shots off the pace.
Portrush's Graeme McDowell, who needs a top-five finish to progress, is joint 35th after a 73 left him one over.
Jim Furyk is tied for the lead after becoming only the sixth player to shoot a magical 59 on the PGA Tour.
Furyk shares the lead with fellow American Brandt Snedeker and the pair are three clear of Zach Johnson.
McIlroy, who opened with a 78, carded a double-bogey at the seventh to go along with six bogeys and two birdies.
The Holywood player has endured a poor 2013 campaign following his decision to switch clubs manufacturer at the start of this season.
Since his move to Nike back in January, McIlroy has failed to win a tournament with his best finish a runner-up spot at the Texas Open a week before the Masters.
McIlroy went into this week's event in 41st place in the FedEx rankings with only the top 30 after the Illinois play-offs tournament going through to the Tour Championship.
The 24-year-old has insisted for the last couple of months that he is close to getting back to his best form and he attributed his latest poor round to "just not scoring".
"I missed it on the wrong side, I'm missing greens with wedges, and just don't have my scoring hat on. I feel like I'm hitting the ball pretty well," said the world number four after Friday's round.
McIlroy had been encouraged by "glimpses" of good form in the first two play-off events but has since regressed after the PGA Tour took a week's break following the Deutsche Bank Championship.
"You come back and you get a card in your hand again, it's a lot different just practising than being out there," added the twice major winner.
"Everything sort of came easy last year," said McIlroy. "Now I'm working harder, hitting more balls, spending more time on the range because I'm searching for it (consistent form).
"And that's what's frustrating. But the fact that I'm working hard and I'm not really getting much out of it, if I can keep patient and keep working hard, I'm sure it'll turn around.
"I'm 24. I've got a lot of time in this game still. I've got obviously a few tournaments left this year."
McDowell was level for his round before a double-bogey seven at the 18th hit his hopes of the making the top five and playing next week in Atlanta.