Colombia's Sebastian Munoz endured a roller-coaster round on his way to an eight-under par 64 Thursday to lead the PGA Zozo Championship while defending champion Tiger Woods struggled to a woeful 76.

The 27-year-old South American star, had two eagles, eight birdies, five pars, two bogeys and a double bogey on his trip to the top of the leaderboard after the opening round at Sherwood Country Club.

"I've become better with managing crazy ups and downs," Munoz said. "I just get out of the way. At first I was like what should I do? Should I be more calm? Should I attack more?

"I just stopped trying to play anything and just keep playing golf. It's just one of those days. It happens."

Woods, a 15-time major winner who defends the Masters title next month, won last year in Japan before the event was moved to suburban Los Angeles due to the Covid-19 pandemic.

He suffered his worst-ever score at Sherwood by two shots from 45 rounds on a course that once hosted his charity event.

Woods, who declined to speak with the media after his round, shared 75th of 77 players in the no-cut event where he hoped to win an unprecedented 83rd career US PGA title.

Instead, Woods matched his worst PGA showing on par-5 holes in any round, going 3-over with a birdie, two bogeys and a double bogey despite at 87-foot birdie putt at the par-4 14th.

Four-time major winner Rory McIlroy snapped a club in frustration on his way to a disappointing 73 -- seven birdies, four bogeys and two double bogeys including at 18 -- over a course that surrendered low scores and birdies in binges to many players.

England's Tyrrell Hatton and American Justin Thomas shared second on 65.

Thomas followed back-to-back birdies at five and six with bogeys on the next two holes, then fired a 29 on the back side with five birdies and an eagle on the par-5 16th.

"I drove the ball well," Thomas said. "I really struggled reading the greens. I knew the course had some birdies out there. It was one of those nines. Then I started hitting it close and rolling the ball a little better."

A fourth-place pack on 66 included South African Dylan Frittelli and Americans Brian Harman, Lanto Griffin, Harris English and Kevin Kisner.

'It was pretty sweet'

Munoz, whose lone PGA victory came last year at Jackson, Mississippi, enjoyed the round of the day despite an opening bogey.

He followed with birdies on four of the next five holes before his first eagle, holing out with a 9-iron from 168 yards at the par-4 seventh.

"I just focused on making the best swing I could and I started four yards left, started cutting nicely towards the pin," Munoz said. "Once you see the guys throw the touchdown sign, it's good."

After a bogey at the eighth, Munoz birdied three of the first four holes on the back nine before a double bogey at 14 when his tee shot landed beside a shrub.

Munoz answered with another eagle at the par-5 16th, holing out from in the fairway from 51 yards, before a final birdie at 17.

"I just throw it up there and find the hole," he said. "It was pretty sweet."

It marked the third time in Munoz's career he made two eagles in the same round.

"It's awesome. It's beautiful," Munoz said of the course. "All par-5s are reachable. Fun par-3s. It's a great place. Anything can happen."

American Gary Woodland, last year's US Open winner, withdrew with a back injury.