Jim Furyk fired a four-under-par 66 to secure a comfortable four-shot lead following the second round of the WGC-Bridgestone Invitational in Akron, Ohio.
Furyk started the day one shot behind overnight leader Danny Lee, who was unable to maintain his early momentum, and carded a two-over-par 72 to fall into a tie for fifth.
World number three Bubba Watson enjoyed a productive time of it on Friday, firing a four-under-par 66 to move into a tie for second with Irishman Shane Lowry (66), and Dustin Johnson (67)
Meanwhile, reigning Masters and U.S. Open champion Jordan Spieth is currently in a tie for eighth after carding a two-under-par 68.
Furyk, who heads into the weekend on eight-under, began his round at the tenth tee, and started with a birdie at the 11th before he stumbled to a bogey at the 12th after missing an eight-foot par putt. However, he recovered to finish his opening nine with consecutive birdies at the 17th and 18th.
Furyk proceeded to make another birdie at the second before recording his second bogey of the round at the third. A sensational 57-foot birdie putt at the fifth was followed by a pair of birdies at the seventh and eighth. The American was unable to end his day on a high though, slipping up with another bogey at the ninth after missing a five-foot par putt.
Watson, who is four shots behind Furyk, followed his first-round 70 with a 66. The world number three made three birdies and a bogey on the front nine before going on to repeat the pattern on the back nine to finish on four-under-par heading into the weekend's running.
Lowry got off to an excellent start, making four birdies and a bogey on the front nine, and went on to register further birdies at the 11th and 15th before completing his round with a bogey at the 18th.
Johnson, who is ranked seventh in the world, did not get off to the best of starts, with bogeys at the third and fifth before producing birdies at the sixth and ninth to take the turn at level-par 35.
The U.S. Open runner-up started the back nine with consecutive birdies at the 13th and 14th before missing a 17-foot par putt at the 15th. The 31-year-old atoned for his mistake by finishing with two more birdies at the 17th and 18th to end the day on four-under.
Sitting five strokes behind Furyk is Lee, who made two birdies and four bogeys in his round of 72, Graeme McDowell (71) and Henrik Stenson (69).
Spieth, who remains six strokes behind Furyk, began his round with a birdie at the 10th before making consecutive bogeys at the next two holes. He made up for that with a pair of birdies at the 13th and 14th before capping off his front nine with a birdie at the 17th.
The world number two started his closing nine with a 20-foot birdie putt at the third before faltering with bogeys at the fourth and fifth. However, the 22-year-old headed into the weekend on a high with a birdie at the ninth to finish the day on two-under.