Ted Potter Jr. threatened to join the PGA Tour's '59 club' on his way to making a significant move up the leaderboard during the third round of the AT&T Pebble Beach Pro-Am.
The world No 246 - without a worldwide victory since the 2012 Greenbrier Classic - played his first seven holes at Monterey Peninsula in seven-under-par to look well-placed to challenge for only the 10th sub-60 round in PGA Tour history.
Potter, who had never previously posted a round lower than 64 on the PGA Tour, then posted four birdies in a six-hole stretch after the turn to get to 11 under for the round and one more birdie away from a career-defining round.
The 34-year-old saw his hopes ended by back-to-back bogeys over his final two holes, with Potter signing for a nine-under 62 to set the clubhouse target at 14 under.
Beginning the day seven strokes off the pace and starting on the back nine, Potter opened with a two-putt gain at the par-five 10th and followed it with a hat-trick of birdies over his next three holes.
Potter's birdie run was briefly halted with a two-putt par at the 14th, only for the American to pick up a shot at the 15th and post an eagle-three at the 16th to go seven under for his first seven holes.
Reaching the turn in 30, Potter holed from off the first green and drained a 25-footer at the second, before a 10-foot gain at the fourth moved him alongside Dustin Johnson at the top of the leaderboard.
Potter had grabbed the outright advantage by the time he rolled in from eight feet at the sixth to go 11 under for the round, leaving him needing one more birdie over the final three holes to shoot sub-60.
The two-time Web.com Tour winner missed the par-three seventh green off the tee but pitched on to save par, only to find the rough with his approach into the next and miss his 12-footer for par.
Needing an ace at the par-three ninth - his final hole - to join an illustrious group of players, Potter's challenge was ended when his tee shot finished in a greenside bunker on his way to a closing bogey.
Watch the final round of the AT&T Pebble Beach Pro-Am live on Sunday from 6pm on Sky Sports Golf and 7pm on Sky Sports Main Event.