Sebastian Munoz (65) grabs one-shot lead at LIV Singapore

Sebastian Munoz delivered his best round of the year, an opening-round 65, to claim a one-shot lead over a tightly packed field at LIV Singapore on Friday.

Munoz stands at 6-under after 18 holes at Sentosa Golf Club's Serapong course with 14 golfers within two shots of his lead. A group of six players one back includes Brooks Koepka, Martin Kaymer, Kevin Na, Thomas Pieters, Cameron Tringale and Abraham Ancer all at 5-under.

"Here it's always go low every day," said Munoz. "Good players behind me, capable, and you know they're going to shoot pretty low. Just keep shooting at the pins, trying to make the putts and hang on."

Koepka turned 34 on Friday and seemingly unwrapped his missing putting stroke to open the round with five birdies in seven holes, and Pieters posted a bogey-free round highlighted by an eagle at the par-5 18th. Pieters posted his sixth sub-par round in a row.

"When you're hot, you're hot. Sometimes you don't have it and you're just playing safe," said Koepka, who felt his putting kept him out of contention at The Masters last month. "You never know what's going to come tomorrow. Playing good. Just need to keep ball-striking it well. It's kind of the last prep I'm going to get for the PGA (Championship), so just trying to make sure everything is in order."

The first round is a correction of sorts for Munoz, who had five bogeys -- three on consecutive holes -- in the closing 10 holes at Adelaide last week.

Munoz said he doesn't always prefer to return to the course after the first round with a lead because of the distraction of casting thoughts to the cumulative score instead of shot-to-shot.

"I've had the lead I think just once after two days. First round maybe twice. It's a tough thing, and it's a stacked field," Munoz said. "The way that LIV Golf works, it's just kind of go low all the time. Sometimes it's a little stressful. So sometimes, yeah, I agree I haven't performed my best."

LIV Golf's individual points leaders this season, Joaquin Niemann, is among the pack of players two shots back.