Vaughn Taylor won his first PGA Tour title in 11 years with a final round 65 in the Pebble Beach Pro-Am.
Taylor, 39, was world ranked 447 at the start of the week and only got into the tournament on Monday as first reserve.
He moved through the field from eighth place overnight and secured victory when Phil Mickelson missed a five-foot putt for birdie on the 18th.
“I don’t even have my tour card – now I am playing in the Masters,” said the American, who finished on 17 under par.
Taylor qualified for the first major of the year in Augusta through Sunday’s win.
Overnight leader Mickelson was trying to win his first tournament in 50 starts since the 2013 Open Championship but a level par final-round 72 left him one shot off the pace.
A three-under 69 took England’s Justin Rose into a tie for sixth.