SAN ANTONIO — First-round leader Si Woo Kim used a late-round hole-in-one Friday to build a four-shot lead at the halfway point of the Valero Texas Open.

Kim, the 2017 Players Championship winner, led by one heading into the second round before shooting a 6-under 66.

Kim aced TPC San Antonio’s 16th hole and is 12 under through 36 holes at the PGA Tour’s last stop before the Masters. He leads six players at 8 under, including Rickie Fowler and Jordan Spieth. Fowler led on the back nine until consecutive bogeys late in the round.

Joining Fowler and Spieth — both shot 68 — are Harold Varner (66), Adam Schenk (66), Kyoung-Hoon Lee (67) and Monday-qualifier Corey Connors (67).

Kim’s ace at the 167-yard 16th bounced up toward the flagstick, landed next to the lip of the cup and dropped in. He’s gone 26 holes without a bogey.