Jordan Spieth offered further evidence that he is returning to peak form with a five under par 65 on the opening day of the Charles Schwab Challenge.
Spieth, a three-time major winner, was joint third at last week's US PGA Championship for his first top 10 since last summer's Open at Carnoustie and his best finish in more than year.
The 25-year-old is renowned for his efficiency on the greens and he put in a career-best performance in strokes gained in putting (5.5), sinking everything inside 15 feet, to sit one shot behind overnight leader Tony Finau.
Former US PGA champions Jason Dufner and Jimmy Walker were among nine players on three under but it was a day to forget for defending champion Justin Rose, who made four bogeys in eight holes on the back nine, as the world number three recorded a four over 74.
Seamus Power and Graeme McDowell were both seven shots behind Finau on one over after contrasting rounds of 71.
Power parred every hole except the 8th (his 17th) while McDowell hit two birdies and three bogeys.
Beginning on the back nine, Spieth was off the green on the 13th but chipped in for the first of four birdies in eight holes, the last of which saw him hole a 30-foot putt to take the lead.
He dropped back after a poor approach at the 18th found a water hazard, leading to a double bogey, but back-to-back birdies immediately after the turn took the 2016 champion back to four under.
Spieth holed a monstrous 46-foot putt on the fourth for another gain before finishing bogey-birdie. In total, he had only 22 putts at Colonial Country Club near Fort Worth in Texas.
Spieth's efforts in his home state put him in joint second alongside Roger Sloan, who hit 15 of 18 greens in regulation to bolster his charge up the leaderboard.
The 32-year-old carded six birdies with the only blemish of his first round arriving when he three-putted the ninth.
Finau, though, is the one to catch after his six under 64 as he bounced back from a modest showing last week at Bethpage, where he was tied for 64th.
The American had placed in the top 10 in four of his previous five majors and decided to switch to a craw grip for his putting, a move which paid dividends as he made seven birdies and just the one bogey.
He told the PGA Tour's website: "I needed to switch something. It's an itch I wanted to scratch. To me, it was just the perfect time.
"I'm left-hand dominant when I roll the stick. I used to putt cross-handed for about five years. I've been putting conventionally now for a couple of years.
"But I just wanted to switch it up. I haven't been putting great. I wanted to try something different, and it felt great out there."