Colombia's Sebastian Munoz fired a stunning 12-under par 60 on Thursday to seize a four-stroke lead at the PGA Tour's Byron Nelson tournament in suburban Dallas.
The 29-year-old from Bogota, whose only PGA title came at the 2019 Sanderson Farms Championship, went 10-under in his last 10 holes to dominate the early starters at TPC Craig Ranch.
"It's a great feeling whenever everything is clicking," Munoz 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."
He was four strokes in front of a quartet of players that featured defending champion Lee Kyoung-hoon of South Korea, Chile's Mito Pereira and Americans Peter Malnati and Justin Lower.
Pereira's 64 was a career-low in his 80th career PGA Tour round. Malnati had two eagles in a round for the first time in his PGA career.
Lee's bogey-free effort at TPC Craig Ranch included an 11-foot eagle at the 12th, while Lower holed out for an eagle at the par-four 10th.
Munoz became the first player in Tour history with two rounds of 60 or better in the same season, having also shot a 10-under 60 in the first round of last November's RSM Classic, where he finished third.
"I think this was a little more impressive. I mean, it was par-72. I never shot 12-under," Munoz said.
"But this one was definitely impressive. That one I was playing with Corey Conners that day and I thought he was going to shoot 59. That kind of inspired me my push.
"Today, I don't know. I just kind of kept it going and I just wanted to get more looks, more looks and more chances, and I just kind of went crazy with it."
The South American rolled in his first birdie at the par-4 second, then holed a 25-foot birdie putt at the par-5 fifth and dropped his approach to three feet at the sixth.
Munoz was way left beyond a cart path off the eighth tee and made his lone bogey before starting his astonishing finish with a 15-foot eagle putt at the par-5 ninth.
World number 73 Munoz landed his approach at the 10th inside three feet, then dropped close approaches at 11 and 12 before sinking birdie and eagle putts.
It marked the second year in a row that Munoz eagled the ninth and 12th holes in the opening round.
Munoz made birdies at 14, 16 and 17. He reached the par-5 18th fairway with a chance at an eagle and a 59, but his second shot sailed way right. He responded by blasting back to 12 feet and sank the putt to complete his stunning round.
"I wanted to give me a chance (at 59)," Munoz said. "Overdid it and ended up with a 60, which is really good around here."
World number one Scottie Scheffler, playing in front of hometown Dallas fans for the first time since winning his first major title at the Masters, was among 13 players sharing 12th place on five-under par 67 - a group that included major winners Jordan Spieth, Hideki Matsuyama, Dustin Johnson and Adam Scott.
60 - Sebastin Muoz (COL)
64 - Mito Pereira (CHI), Peter Malnati, Lee Kyoung-hoon (KOR), Justin Lower
65 - Kyle Wilshire
66 - Seamus Power (IRL), Carlos Ortiz (MEX), Charl Schwartzel (RSA), JJ Spaun, David Skinns
67 - Christiaan Bezuidenhout (RSA), Matt Kuchar, Hideki Matsuyama (JPN), Dustin Johnson, Scott Stallings, Conrad Shindler, Matthias Schwab (AUT), Joaquin Niemann (CHI), Adam Scott (AUS), Jordan Spieth, Scottie Scheffler, Ryan Palmer, Dawie van der Walt (RSA)