Colombia's Sebastian Munoz holds a four-stroke lead after his spectacular 12-under first round at the AT&T Byron Nelson, breaking the course record by two.
After a solid start to his round, with three birdies and one bogey from his first eight holes, Munoz found another gear the rest of the way.
An eagle on the ninth got things started, followed by birdies on 10 and 11 before another eagle on 12. After one birdie and two pars, he finished his round with three more consecutive birdies.
The round was Munoz's second 60 of the season, incredibly making him the first player in PGA Tour history to accomplish the feat twice in the same season, having also posted a 12 under score in the opening round of November's RSM Classic at Sea Island Resort.
Speaking to the media after his round, he said it was a pleasure to be in such good touch.
"It's a great feeling whenever everything is clicking, hitting the tee shots, ball is coming out in the window that you imagined, you're reading good the putts well," he said.
"When everything is going, it's just stay out of the way and just kind of let it happen – so that's what I did.
"I had a tough putt on 12 for eagle and like I was thinking like, it's okay if I don't make this one. Then it was like, I know I can make it, just kind of stay in it, trust what you're doing ... I made it.
"It was a great stretch and [I'm] really happy."
Reigning champion Lee Kyoung-hoon sits in second place after a bogey-free, eight-under 64, highlighted by an eagle on the par-five 12th.
Tied with Lee at eight under are Chile's Mito Pereira and American Peter Malnati, with the latter picking up a two-shot eagle on the par-four 13th.
A pair of Americans – Justin Lower and Kyle Wilshire – are one more shot back at seven under in a tie for fifth, while there is a strong international contingent consisting of Mexico's Carlos Ortiz, South Africa's Charl Schwartzel, and Ireland's Sheamus Power at six under rounding out the top-10.
There is a star-studded group at five under in a strong position, including Masters champions Scottie Scheffler, Hideki Matsuyama, Adam Scott and Jordan Spieth.
Australia's Jason Day is beginning to find some form, finishing his round at four under along with Justin Thomas, Aaron Rai and Trey Mullinax – who eagled back-to-back holes on 12 and 13, but had a triple-bogey on the first and bogeys on two and three to balance it out.
On a day with relatively friendly scoring conditions, there were disappointing rounds of one under from Will Zalatoris and even par from Xander Schauffele, Davis Riley and Tommy Fleetwood, while Kevin Kisner, Sam Burns and Talor Gooch will be fighting to make the cut at one over.