Patrick Reed made a deft par-save at the final hole to hold a one-shot lead over Abraham Ancer after the third round at the Northern Trust in New Jersey on Saturday.
While overnight frontrunners Dustin Johnson and Jordan Spieth struggled, Reed carded a four-under-par 67 in testing winds on the exposed Liberty National course.
At 14-under 199, the American has his sights set on what would be his first victory since last year’s Masters.
Mexican Ancer three-putted the 16th hole before parring the last two for a 68 that left him alone in second place in the first of three FedEx Cup playoff events on the PGA Tour.
American Brand Snedeker had the round of the day, a 63 that lifted him within two strokes of the lead along with Spaniard Jon Rahm (69).
Halfway leader Johnson battled to a 74 and slipped five shots behind.
Spieth, who teed off one shot from the lead, also carded 74 and fell six adrift.