Charlotte-born Bill Haas will take a two-stroke lead in the second round of the Wells Fargo Championship.
The 28-year-old carded a bogey-free round of 64 to end the opening day in North Carolina on eight-under, while Jonathan Byrd and David Toms enjoyed almost flawless rounds to finish six-under.
Haas said afterwards: “I putted well, which leads into everything.
“It makes you more comfortable over your iron shots knowing that you can maybe miss this shot and your putter might save you. I just had the good feelings going with it.”
He was in fine form with his putter around the Quail Hollow Club course, using just 26 strokes, and he also hit 10 out of 14 fairways and 15 out of 18 greens in regulation.
Starting at the 10th, the American began the day in fine fashion with birdies at two of the first three holes, and two more at the par-four 14th and par-five 15th ensured he made the turn in 28.
Haas showed no sign of letting up on his back nine and notched another four birdies to sign for 64, with the last one coming at the par-four eighth hole.
Haas birdies the eighth hole
Byrd, meanwhile, racked up seven birdies in his opening round, with one bogey, to keep in touch with the leader, and he was joined on six-under by Toms whose bogey at the par-three 17th was only the blot on a fine day’s play that saw him make five birdies and an eagle, which came at the par-five seventh.
Lucas Glover and Pat Perez are a shot further back, while the likes of Padraig Harrington and Sergio Garcia remain in contention at three-under, along with bookmakers’ favourite Phil Mickelson.
Mickelson endured a rollercoaster run from holes four to six with two birdies sandwiching a bogey, but he made sure he would remain touching distance with the early pacesetters with four successive birdies around the turn to sign for 69.
He said: “I hadn't played in a few weeks, and to shoot under par was a good start.
“It could have been a lot better, it could have been a lot worse. I'll certainly take it. I have some areas I can improve and have some areas that I did very well today. It was fun.”
But defending champion Rory McIlroy had a day to forget as he hit just eight fairways and 10 greens, taking 32 putts, in a disappointing three-over-par round of 75.
The Northern Irishman, who turned 22 on Wednesday, wrote on his Twitter account afterwards: “Not the start I was looking for!
“Struggled with my balls striking today which is unusual for me. Hit it better on the range afterwards.”