Jimmy Walker retained his slim advantage over the US PGA Championship field at the turn of his final round, just a shot clear of Jason Day and Henrik Stenson.
Overnight leader Walker - looking to become the tournament's seventh wire-to-wire champion - was even par through nine holes at Baltusrol with a blemish-free, if birdie-less 34, to maintain his score of 11 under.
Both Stenson and Day had their wobbles, the defending champion especially, as they tried to hunt down Walker.
Stenson had to rescue par at the seventh, having picked up a shot at six, but got the job done with a bunker shot that put him within three feet of the hole.
Day was left reeling after bogeying the first and third holes, but a 75-yard putt at five reversed momentum and a sumptuous tee shot at the par-three ninth left him with a tap in to put more pressure on Walker.
Branden Grace set the clubhouse lead at nine under, having picked up three shots on his front nine and birdieing 13. A bogey at 16 left him just off the pace of Walker, but the South African - third at Whistling Straits last year - was delighted with his efforts.
"This is the best I've hit the ball in a long time," he told Sky Sports. "The putter wasn't as hot as it could be, but it was nice. I really enjoyed it out there.
"Anything can happen on a golf course like this. That's the beauty of that finish."
Brooks Koepka parred 10 holes in a row before a bogey at 11 left him three shots off Walker, tied for fifth with Hideki Matsuyama.