A stunning 12-under 60 gave teenager Blades Brown a share of the lead with world number one Scottie Scheffler after the second round of the American Express in California.
The 18-year-old’s eye-catching 10 birdies and an eagle put him on 17 under alongside his fellow American.
On his first PGA Tour appearance of the season, Scheffler followed up his opening round of 63 with an eight-under 64.
The 29-year-old made three birdies on the front nine at in La Quinta, before another five followed for a second consecutive bogey-free round.
Scheffler has yet to win the American Express tournament, which boasts a prize of £1,236,000 ($1.656m) for the champion.
South Korea’s Si-Woo Kim is a shot behind the leaders after a round of 65 left him at 16 under, while compatriot Seong-Hyeon Kim and American Matt McCarty are a further shot back.