Si Woo Kim opened with a 6-under par 66 at TPC San Antonio and will take a one-stroke lead into Friday’s second round of the Valero Texas Open.

Kim, who was paired with Kyle Stanley (70) and Jonas Blixt (72), finished his first day at the AT&T Oaks Course with two bogeys against eight birdies, including five in a six-hole stretch to secure the day-one lead.

The 23-year old Korean, who hit 9 of 14 fairways and 13 of 18 greens, cited ball-striking as the key to his day.

“We are playing more earlier (in the season), so the course is playing a little bit longer and harder, and the grass is a little different,” said Kim. “But today, my driving and irons were good, and I putted well. That’s why I played good.”

Jhonattan Vegas was among four players one further back on 5 under. The former Texas Longhorn bogeyed the first hole, but finished clean the rest of the way, adding 11 pars and six birdies, highlighted by four-straight gains on Nos. 11-14.

“Obviously a great day,” said Vegas. “Besides having a fever last night, dealing with allergies right now. I mean, withdrawing crossed my mind last night.

“So from there to 5 under today, obviously an extremely good day. I didn’t know what I was expecting today, so super happy with a 5-under par.”

Joining Vegas in the T2 group were J.T. Poston, Brian Stuard, and Abraham Ancer.

Rickie Fowler and Jordan Spieth headlined a block of 11 more players tied at 4-under par.

The two superstars produced identical five birdie/one bogey rounds of 68.

For Spieth, it’s the first time he’s been anywhere near the lead since the Genesis Open, some two months ago.

“Yeah, stroke feels good. Struggled a little with the swing to start, just didn’t hit a whole lot of fairways,” said Spieth, who hit just 5 of 14 fairways, but found 13 of 18 greens.

“But I kept the ball in between the beacons, didn’t hit any out of play, and therefore was able to kind of play a bogey-free type of golf and take advantage of the par 5s.”

A logjam of 16 more players were 3-under par, including Matt Kuchar, J.B. Holmes and Graeme McDowell.

TOP-5 LEADERS

1. Si Woo Kim -6
2. J.T. Poston -5
2. Abraham Ancer -5
2. Brian Stuard -5
2. Jhonattan Vegas -5

OTHER NOTABLES

6. Rickie Fowler -4
6. Jordan Spieth -4
17. Matt Kuchar -3
17. J.B. Holmes -3
17. Graeme McDowell -3
33. Jimmy Walker -2
33. Jim Furyk -2
52. Charley Hoffman -1
52. Ernie Els -1
52. Andrew Landry -1
52. Daniel Berger -1
52. Martin Kaymer -1
74. Davis Love III E

STAT LEADERS

Driving: Trey Mullinax – 333 yards
Fairways: Ryan Moore – 13/14, 92.9%
Greens: Shawn Stefani – 15/18, 83.3%
Putts/GIR: Smylie Kaufman – 1.300

ROUND 1: VIDEO HIGHLIGHTS