World number one Dustin Johnson and Webb Simpson made flying starts during the early stages of The Players Championship on Thursday.
Starting at the 10th, Johnson was six under par through 12 holes without a blemish on his card.
Johnson, who this week told Omnisport that he believes he can win the tournament for the first time if he putts better at TPC Sawgrass, found all greens in regulation on his opening nine holes, making birdies at the 11th, 12th, 14th, 16th and 18th before adding a further gain at the second.
Simpson, also starting at the 10th, was through 14 holes having made seven birdies and just a solitary bogey at 13.
Kim Si-woo, Kevin Mitchell and Nick Taylor were all a stroke behind the leading duo.
Of the morning starters, the signature group of Rory McIlroy, Jordan Spieth and Justin Thomas endured some struggles.
McIlroy was one under by the turn but slipped back to even par through 11, while Spieth and Thomas were both three over having played the same number of holes.
Tiger Woods, Phil Mickelson and Rickie Fowler – all playing in the same group – are among the day's later starters.