Munoz joined in three-way tie after second round of AT&T Byron Nelson
After breaking the course record by two strokes in the first round, Sebastian Munoz is now in a three-way tie atop the AT&T Byron Nelson leaderboard heading into the weekend.
Munoz, who is the first player in PGA Tour history with two rounds of 60 in the same season, shot a solid three-under 69 to move to 15 under, where he was joined by Ryan Palmer and David Skinns, who posted respective Friday scores of 62 and 63.
Palmer's 62 was the outright round of the day, with 10 birdies and no bogeys, while Skinns was the only other player to shoot better than 64 after 10 birdies and one bogey.
Justin Lower is one stroke back in outright fourth place, while Charl Schwartzel sits at 13 under in outright fifth.
A strong three-man group is tied for sixth at 12 under, consisting of Jordan Spieth, reigning champion Lee Kyoung-hoon and Chile's Joaquin Neimann.
After Neimann's rounds of 67 and 65, he told the media he knew it would be a low-scoring tournament, and to compete he would need to play with aggression.
"You know that before the start of the week ... this is one of those courses that they score pretty low, so you kind of have that mindset a little bit before the tournament," he said.
"I know 12 under was really impressive, but yeah, you know they're going to go pretty low during four days."
Fellow Chilean Mito Pereira is part of the group at 11 under that rounds out the top-10, tied with Hideki Matsuyama and four others.
Justin Thomas remains in the mix at 10 under, while Masters champion Scottie Scheffler is breathing down his neck a shot back.
The Australian duo of Jason Day and Adam Scott are joined by Aaron Rai at eight under, and are likely in the last grouping that could hope to potentially figure in the finish.
With the cut-line at five under, Xander Schauffele snuck through after going eight under from his last 10 holes, while Will Zalatoris, Luke List and Sam Burns missed out by one stroke, with Bubba Watson one further shot back.