American John Huh earned a one-point lead at the Barracuda Championship in Nevada on Thursday.
The PGA Tour tournament is famed for its use of the Modified Stableford scoring system, with points given for an albatross (eight), eagle (five) and birdie (two) and points subtracted for a bogey (minus one) and double bogey or more (minus three).
Huh made a fine start, holing eight birdies and dropping just one shot to be clear with 15 points following the opening round at the Montreux Golf and Country Club.
Huh - the winner of the 2012 Mayakoba Golf Classic - teed off from the back nine and birdied his first hole as he also collected two points at the 12th, 13th, 14th, 18th before carding three birdies after the turn.
Miguel Angel Carballo and Stuart Appleby are second with 14 points apiece heading into the second round.
A point back is Brandon Hagy, alongside Ben Martin, Ryan Palmer, Dicky Pride, Patton Kizzire and Rick Lamb.
Defending champion Greg Chalmers ended the first round with 11 points thanks to seven birdies.
The round's worst performer was Tom Morton, who finished minus 11.