The 30-year-old South Korean put himself in position to break 60 with a curling 17-foot birdie putt from the fringe on the par-3 17th at TPC Craig Ranch. It was his 12th birdie of the day, putting him at 12 under on the par-71 layout.
Kim was in the fairway on the 18th, but blasted his second shot over the green. His chip coming back stopped about 19 feet short of the hole, and his putt for par lacked pace and broke to the right for his only bogey of the day.
Kim shot 11-under 60 for a five-shot lead at 18-under 124 after two rounds.
The 18th hole at Craig Ranch is a par four for the first time in the six Nelson tournaments it has hosted. A $25 million overhaul designed by Lanny Wadkins changed it from a par five, and it has played as the hardest hole on the course through two rounds.
Kim, playing with world No.1 Scottie Scheffler and five-time major winner Brooks Koepka, took full advantage.
The four-time PGA Tour winner already had seven birdies through 10 holes when he put his 166-yard approach shot at the par-4 11th inside three feet.
Needing just one birdie over the final three holes for a 59, Kim missed by inches on the par-4 16th. Hopes dimmed with his tee shot on the stadium hole at 17, until he dazzled by far the biggest of any of the galleries on the course with a perfect putt.
"I hit it great and putted great," Kim said. "So everything was perfect, other than the last hole. I'll still take it. Sixty is hard, but I was a little bit of thinking about the 59 after I make that on 17. It was a little bit of like adrenaline."
Jim Furyk has the PGA Tour's 18-hole record with his 58 from the 2016 Travelers Championship at TPC River Highlands. A 59 has been recorded 14 times, including by Furyk and Scheffler, who shot his at TPC Boston in 2020.Â
"I definitely wasn't going to tell him anything about his round today as we were out there," Scheffler said. "I would say it would definitely be in poor taste to remind somebody they're on 59 watch."
The 59 watch overshadowed Scheffler's eight-under 63, which left him five shots back in second place, tied at 13 under with Kim's fellow South Korean, Sungjae Im, Japan's Kensei Hirata and Wyndham Clark. Im aced the par-3 seventh and shot 61.
"I feel like, when you're watching somebody like Si Woo, especially when you're paired with him, just watching somebody birdie every hole and you feel like the tournament is getting further and further away from you," said last year's winner Scheffler.
"I think I did a good job of staying patient and not forcing things."
Australians Karl Vilips (70, 68) at four under and Cam Davis (74, 66) at two under missed the six-under cut.
12°C