The 24-year-old rookie from Texas had six birdies on both the front and back nine in a bogey-free tour of TPC Boston to become the 12th player with a sub-60 round on the US PGA Tour.
Scheffler, the second-youngest to manage the feat, was one shy of the all-time tour record score of 58 set by Jim Furyk in the final round of the 2016 Travelers Championship.
Scheffler, who broke the course record by two strokes, was on 13-under 129 for 36 holes and level atop the leaderboard with Australia’s Cameron Davis, who followed his opening 64 with a 65 on Friday.
It was the second 59 of the year for Scheffler, who fired the score in a casual round in Dallas while the tour was shut down due to the COVID-19 pandemic.
Scheffler made 23 putts and reaching 16 of 18 greens in regulation despite finding only seven of 14 fairways.
Download our app and read this and other great stories on the move. Available for Android and iOS.