Instead, he'll have to settle for a share of second place with Cauley, who had three straight late birdies.
Webb Simpson started one stroke back and a short while after his birdie on the par-5 No 5 - the easiest hole on the course this week - was part of a six-man logjam that shared the lead at 12-under.
Joining him were English, Clark, Garcia, Pettersson and second-round leader Jimmy Walker.
English was the first to backslide with a bogey on the 11th. Walker fell off the pace with a bogey on the 10th.
Simpson ran into trouble late in his round with consecutive bogeys on the 15th and the 16th, his 71 dropping him four strokes back.
Dufner finished with birdies on three of his final four holes to sneak up the leaderboard.
Justin Leonard, who shot a 64, started at four-under and used a steady stream of birdies to make his climb. He needs a high finish to earn enough points to qualify for the playoffs, which begin next week at The Barclays.
Jeff Overton had the first hole-in-one of the week - and his first on the tour - on the par-3 12th.
- AAP