William McGirt has recorded an opening-round 64 to establish a three-shot lead at the Bridgestone Invitational.
The American produced a faultless performance that included six birdies to move clear of Jason Day, Jimmy Walker and Emiliano Grillo.
Jordan Spieth and Rickie Fowler are among a group of four players who are in a tie for fifth and four shots off top spot, while US Open champion Dustin Johnson and Justin Rose remain in contention in ninth place.
Debutant Andrew Johnston is in 18th position alongside fellow Englishman Paul Casey, but Phil Mickelson is off the pace after shooting a round of 73.
Defending champion Shane Lowry registered a score of 76 and sits in 51st place.
