Kim Si-woo fired nine-under-par 62 in the second round of the PGA Tour's WM Phoenix Open, climbing 84 spots on the leaderboard to position himself for a weekend charge.
The 31-year-old Korean carded one eagle, nine birdies, and one bogey at TPC Scottsdale's Stadium Course (par-71) in Scottsdale, Arizona, on Thursday local time.
Kim's two-day total of seven-under-par 135 left him tied for fifth, four strokes behind solo leader Ryo Hisatsune of Japan at 11-under.
The strong performance continues Kim's impressive early-season form. He has posted a tie for 11th at the Sony Open, a tie for sixth at the American Express, and a tie for second at the Farmers Insurance Open since the season began.
After opening with a two-over-par 73, Kim attacked early in the second round. He bogeyed the par-5 10th hole, his first of the day, but quickly recovered with a birdie at the par-3 12th.
Kim then holed an approximately 8-meter eagle putt at the par-5 13th before rattling off three consecutive birdies from the par-5 15th through the par-4 17th.
His momentum carried into the back nine. Kim added consecutive birdies at the par-4 second and par-5 third holes, then closed with birdies at the par-4 sixth and par-4 ninth.
Kim's ball-striking was sharp throughout the round, hitting 92.9 percent of fairways off the tee (13 of 14) and reaching 94.4 percent of greens in regulation (17 of 18).
"Yesterday, my iron shots were a bit shaky. It was the first time this season, so I was worried about hitting the ground before the ball," Kim said after the round. "I tried to focus only on making good impact, and after a few good shots, I felt comfortable throughout the round."
"Starting the first three tournaments of the season so well has helped me relax a bit. It gave me a sense that I could stay comfortable throughout the season. Yesterday, being too comfortable was actually the problem, and that seems to have reignited the fire in me."
World No. 1 Scottie Scheffler of the United States shot a bogey-free four-under 67 to move into a tie for 28th.
Kim Joo-hyung, who had been struggling in the lower half of the field, also rallied with a five-under round to reach three-under for the tournament, tied for 37th.