American Russell Henley took the lead while a charging Rory McIlroy lurked ominously just two strokes off the pace after the third round of the Deutsche Bank Championship in Norton, Massachusetts on Sunday.
Henley carded a six-under-par 65 to seize control of the tournament at 12-under 201, one shot ahead of compatriot Billy Horschel (67) with one round left at the TPC Boston.
But world number one McIlroy made his presence felt with a sizzling 64 to join Australian Jason Day (69) and American Chris Kirk (64) in a tie for third at 10-under.
Northern Irishman McIlroy, seeking his fourth PGA Tour victory in five starts, almost holed out at the 15th and 16th holes, tapping in from inside a foot both times.
The Deutsche Bank Championship is the second of four events in the PGA Tour's lucrative FedExCup playoff series.
(Reporting by Andrew Both in Cary, North Carolina; Editing by Mark Lamport-Stokes)