Scott Piercy opened with four consecutive birdies on his way to a seven-under par 64, seizing a three-stroke lead after Friday's second round of the US PGA Tour's 3M Open.
The 43-year-old American's bogey-free round put him on 13-under 129 after 36 holes at TPC Twin Cities in Blaine, Minnesota.
"It feels great," Piercy said. "It has been a little bit since I've played like I should play. To prove it to myself again, I know it's in there, it's just like, 'OK, how do we get it out of me?'"
Argentina's Emiliano Grillo, chasing his first PGA victory since 2015, was second on 132 with England's Callum Tarren third on 134 after a sizzling 63, one off the course record.
Piercy, a 2016 US Open runner-up, chases his fifth PGA title, but his first solo crown since the 2015 Barbasol Championship. He is 1-4 with a 36-hole PGA lead, winning at the 2012 Canadian Open.
"There's a lot of business to take care of this weekend," Piercy said. "But to come out the first two days and do what I did gives me a lot of confidence going into the weekend."
Back-nine starter Piercy, ranked 297th in the world, shared the 18-hole lead and charged at the start in round two with a birdie binge.
Piercy sank a 27-foot birdie putt at the 10th, a 10-footer at 11, another from just outside four feet at the par-5 12th and the last from just under six feet at the par-3 13th.
It was the third time in his PGA career that Piercy began a round with four birdies after the third rounds at last year's Palmetto Championship and the 2019 Heritage tournament.
Piercy made a 17-foot birdie putt at the second hole and added birdie putts from just outside 10 feet at the par-5 sixth and par-4 seventh.
Grillo, third at the 2020 3M Open, had five birdies and an eagle against a lone bogey.
"I played great. Everything worked," Grillo said. "Made some putts. Happy days."
World number 132 Grillo, who shared second three weeks ago at the John Deere Classic, won his only PGA title at the 2015 Frys.com Open in only his eighth tour start.
Grillo had five birdies and an eagle against a lone bogey. He holed a 40-foot eagle putt after reaching the green in two at the par-5 sixth.
"When you have such a long putt you're trying to focus on the speed," Grillo said of his effort at the sixth hole. "I was just trying to read the break and I hit a magnificent putt."
- Old faithful -
PGA rookie Tarren, ranked 335th, used a new putter in his opening round and fired 71 but went back to his familiar flatstick on Friday.
"I put my old faithful back in today and it worked. Great round," Tarren said.
Tarren, sixth at the John Deere, hit all 18 greens in regulation and said he's playing better because he's more comfortable with the tour.
"My confidence is high and I want to win a golf tournament," he said. "My mindset has almost totally changed from just wanting to make cuts."
South Korean Im Sung-jae, who shared the 18-hole lead with Piercy on 65, was six adrift on 135 along with Americans Tony Finau, Tom Hoge, Doug Ghim and Robert Streb.