Nick Dunlap became the first player to win PGA Tour events as a professional and amateur in the same year with victory at the Barracuda Championship.
Dunlap, 20, topped the leaderboard ahead of fellow American Vince Whaley at the event in California, which uses a version of the Stableford points-based scoring system.
He had seven birdies and an eagle in his bogey-free nine-under 62 final round on Sunday to earn 19 points and seal a two-point victory at the Tahoe Mountain Club.
In January, Dunlap became the first amateur since Phil Mickelson in 1991 to win a PGA Tour title when he triumphed at the American Express Championship.
He turned professional a week after that victory, having earned a two-year exemption on the circuit as well as entry to the Masters, the US PGA Championship and the Players Championship.
Assessing his unique double, Dunlap said: “I never thought that I would have my name next to that, but it’s definitely an honour.
“It’s been a little tough after AmEx. You kind of lose a little bit of confidence and wonder if you can do it again.”
Dunlap, whose latest win earns him a shade over £550,000, emulated Tiger Woods last year by becoming the second player to win both the US Junior Amateur and US Amateur titles.