Colombian Camilo Villegas got the jump on the field on the opening day of the Texas Open after shooting an eight-under 64 with Jordan Spieth among those not far behind.

After starting on the back nine with a bogey, Villegas hit six birdies in seven holes, including sinking a 20-foot putt on his 13th to claim a solid lead at TPC San Antonio's Oaks Course on Thursday.

Villegas is two shots ahead of South Korean Sung Kang and American Cameron Tringale who both had a 66.

Three-time Major winner Spieth is equal third on 65, alongside Noh Seung-Yul and Hideki Matsuyama.

"Sometimes it goes your way, and sometimes it doesn't," Villegas said. "The last few years I've been up and down with many things. We keep showing up and the results start showing up."

Three-time Masters champion Phil Mickelson had a nightmare when he had a 10 on the par-five 18th to finish the day 15 shots back to end up 79.

Mickelson took two penalty shots and another three strokes trying to navigate a greenside stream and nearby rocks on the last and faces a battle to make the cut.

Phil Mickelson recorded a 10 on the 18th hole tying his second highest score on TOUR. pic.twitter.com/fxyX7IMDq1
— PGA TOUR (@PGATOUR) April 1, 2021

Kang started slow but hit an eagle on his 11th hole, jarring a 30-foot putt after two fantastic set-up shots on the par-five. He birdied three of his final four holes.

"I struggled a little bit with a new driver from the start, but I found a way to hit it on the back nine so started driving a lot better," Kang said.

Tringale made seven birdies including four on the back nine to finish with his six-under 66 to be firmly in contention.

Spieth had seven birdies and two bogeys in his round, including a bright start where he birdied three of his first five.

The Texan, who is now ranked 67th, is looking for his first win since the 2017 Open Championship.

"Overall with the score, I certainly would have signed up for five-under starting out," Spieth said.

"Five-under around this track is a good score. I'd take four more of them."

Matsuyama rolled in a 25-foot birdie putt on the eighth as he put together a strong round along with Noh, who is yet to make a cut this season.

Leaderboard after Round 1 @ValeroTxOpen:

1. @CamiloVillegasR -8
T2. @CamTringale -6
T2. Sung Kang
T4. @JordanSpieth -5
T4. Seung-Yul Noh
T4. Hideki Matsuyama
T7. Scottie Scheffler -4
T7. @JSMunoz23
T7. @HogeGolf
— PGA TOUR (@PGATOUR) April 2, 2021