Zach Johnson of the United States lines up a putt on the tenth green during round one of the Sony Open In Hawaii at Waialae Country Club on Friday in Honolulu, Hawaii.
He reached the green in two at the ninth, making a 17-footer for eagle for a ideal finish to his round.
Harman entered the final round of the Sentry Tournament of Champions paired with eventual victor Dustin Johnson.
Johnson admitted his round was a pleasant surprise, after a bout of flu cost him some pre-season practice time. "My swing kind of felt better and better as the day went on".
"I've probably been off long enough now that you never know what's going to happen", he said.
"I had a great day today, and I'm about to go do it. It's laziness, I guess, not doing it consistently over the last couple of years".
The quartet of Vaughn Taylor, Kyle Stanley, Talor Gooch and Brian Harman are one shot adrift of the leaders after all shot 64s. He wound up with a quadruple-bogey 8, marring his eight-birdie round for only a 69. That was first of three straight birdies, and he had ample more opportunities, including a shot that hit the pin on No. 10 and settled 3 feet away.
Japan's Daisuke Kataoka and Americans Peter Malnati, Matt Every and Tom Hoge all shot 65.
Jordan Spieth has already made a number of long, highlight-reel putts in his five years on the PGA Tour, none more impressive than his bounce back eagle on Royal Birkdale's 15th hole during the final round of the Open Championship.
Spieth's next two shots also hit wood and stayed in the rough before he managed to gouge his fifth shot into a greenside bunker, from where he took three more to get down as he tumbled down the leaderboard to level par.
Defending champion Justin Thomas, who a year ago opened with a 59 before going on to set the tour's all-time scoring record in a 72-hole event at 253, could not conjure up that same magic as he carded a three-under 67, four back of the leaders. He picked up an unlikely birdie on the 13th from the fairway bunker by making a 25-foot putt, and he made a 20-foot birdie on the next hole.
Thomas had five-time major champion Phil Mickelson's former caddie, Jim "Bones" Mackay, on his bag since his usual looper was unavailable due to injury.