Bryson DeChambeau carded a course record-equalling 62 - his lowest score on the PGA Tour - to take a two-shot lead after the second round of the 3M Open in Minnesota.
The 25-year-old, who has yet to make a bogey this week, reeled in overnight leader Scott Piercy, who could manage only a 70, on his way to reaching 14 under at the halfway stage.
Canadian Adam Hadwin retained second place, now on his own, with his seventh birdie of the round coming at the last to allow him to sign for a 67.
That was two ahead of Piercy, Sam Saunders, Brian Harman and Sam Burns.
Of DeChambeau's nine birdies, four came via putts of more than 19 feet, helping him to a career-low 36-hole total of 128.
"Certainly, me doing that today inspires me to even do better over the weekend," DeChambeau, who has one win and four top-10 finishes in the 2019 season, told pgatour.com.
"I know I can do it. I know I still left a couple out there, lipped out a couple of short putts. Although I made a lot of putts, I'm not going to take that for granted.
"Whenever I can roll a couple of putts in from 20 feet or more, that gives you a lot of confidence for the game.
"And when you're striking it well and driving it where you're looking, that's obviously very positive.
"I know it's cliche to say that, but it's just what it is unfortunately. Kind of get into a rhythm a little bit, the zone, and it just feels good sometimes."
