Washington - Bryson DeChambeau fired a nine-under par 62, the lowest round of his US PGA career, to seize a two-stroke lead after Friday's second round of the 3M Open.
The 25-year-old American stood on 14-under 128 after 36 bogey-free holes, having matched the course record at TPC Twin Cities in Blaine, Minnesota.
Canada's Adam Hadwin fired a 66 to stand second on 130 with Americans Scott Piercy, Brian Harman, Sam Burns and Sam Saunders in the clubhouse on 132. India's Arjun Atwal and Australian Curtis Luck were among those on 133.
DeChambeau made more than 137 feet of putts on Friday, when he began on the back nine. He birdied the par-5 12th, drained a 19-footer on the par-3 13th and a 21-foot putt two holes later.
Making his turn onto the front side, DeChambeau birdied six of the first eight holes.
"I made a couple more putts outside 20 feet, definitely converted on the par-5s, certainly wedging was a lot better," DeChambeau said when comparing his second round to his first.
"When you do that well, you're going to have a low round."
DeChambeau said he has made a slight change that has improved his putting, keeping the change to himself.
"It has been through a lot of practice, trial and error and struggle," he said. "I've been through a lot of that struggle but that's what makes me better. It's just a learning process. I'm learning every single day.
"My focus is to just keeping driving as well as I have. I can make the putts. If I continue to drive it this well, that's the Bryson of last year."
DeChambeau enjoyed great success in 2018, winning the Memorial tournament, the Northern Trust and Dell Technologies Championship in the US PGA playoffs and last November's Shriners Hospitals for Children Open at the start of the current campaign.
He's going for a sixth career US PGA title this week, having also taken the 2017 John Deere Classic.
It would be his second trophy of the year overall, having won the European Tour's Dubai Desert Classic in January by seven strokes.
Hadwin sank a 17-foot birdie putt at the second but followed with back-to-back bogeys. He holed a 14-foot birdie putt at seven, birdied three in a row to start the back nine then birdied two of the last three holes, from 17 feet at the 16th to seize second alone and 3.5 feet at 18 to trim his deficit to two shots.
Leading scores after Friday's second round of the US PGA Tour 3M Open at Blaine, Minnesota (USA unless noted, par-71):
128 - Bryson DeChambeau 66-62
130 - Adam Hadwin (CAN) 64-66
132 - Scott Piercy 62-70, Sam Saunders 65-67, Brian Harman 65-67, Sam Burns 66-66
133 - Arjun Atwal (IND) 65-68, Curtis Luck (AUS) 68-65, Scott Brown 68-65, Kevin Streelman 68-65
134 - Carlos Ortiz (MEX) 67-67, Troy Merritt 70-64, Brendan Steele 66-68, Charles Howell 68-66, Denny McCarthy 66-68, Roger Sloan (CAN) 67-67, Adam Svensson (CAN) 70-64, Colin Morikawa 68-66, Tony Finau 66-68, Corey Conners (CAN) 70-64, Hideki