Los Angeles - Journeyman Adam Long birdied the final hole on Sunday to seize his first PGA Tour title at the Desert Classic ahead of five-time major winner Phil Mickelson and Adam Hadwin.
Long, a 31-year-old American ranked 417th in the world, only made his way onto the PGA Tour this season via the Web.com Tour.
He had seven birdies without a bogey in his seven-under 65 for a 26-under par total of 262 and the win in his sixth career PGA Tour start.
"I'm in disbelief right now," Long said. "I don't really know what just happened, but I'm thrilled."
Playing in the final group for the first time alongside Mickelson and Hadwin - a Canadian with three top-10 finishes in the past three seasons in the California desert - Long said the attention on his better-known playing partners left him "kind of in the background doing my thing."
The trio were tied at 25-under heading into the par-four 18th on the Stadium Course, one of three courses used in the tournament.
Facing a second shot from an awkward lie below his feet, Long stuck it 14 feet from the pin as Mickelson fired out of the rough to 38 feet and Hadwin found the back greenside bunker.
Mickelson, who had led all week since a sensational opening 60, settled for a par and a three-under 69 for 15-under 263, where he was joined by Hadwin who also parred the last for a five-under 67.
Long, who twice chipped in for birdie on the back nine, said that Mickelson's first putt at 18 gave him a good indication of what his putt would do.
"It was one of those putts that you stand over and you just know you're going to make," he said. "You can't control that, but when you have that feeling it's a good one."
Mickelson struggled on the greens all day, starting with a three-putt bogey at the first.
Mickelson finished with five birdies - draining a six-footer at 15 and a 10-footer at 16 to regain a share of the lead.
Overall, however, he called it an "awful" day with the putter.
"Terrible putting day, one of the worst I can recall in a while," said the 48-year-old who was in search of a 44th career title. "I hit a lot of good shots today, but I just couldn't get the ball to go in the hole."
Hadwin had taken control with six birdies in the first 11 holes.
He still held a two-shot lead after his only bogey of the day at 13, but he couldn't find another birdie the rest of the way and Mickelson and Long closed the gap.
It was another near miss in the event for Hadwin, who carded a third-round 59 on the La Quinta course in 2017 but settled for second place. He finished tied for third last year.
"It would have been a special moment if I could have pulled it off," Hadwin said. "But there's always next year I guess."
Leading final-round scores on Sunday in the PGA Tour Desert Classic in La Quinta, California (par-72; USA unless stated):
262 - Adam Long 63-71-63-65
263 - Phil Mickelson 60-68-66-69, Adam Hadwin (CAN) 65-66-65-67
264 - Talor Gooch 67-67-66-64
266 - Dominic Bozzelli 67-69-64-66
267 - Jon Rahm (ESP) 66-66-68-67
269 - Vaughn Taylor 68-66-69-66, J.T. Poston 68-68-64-69
270 - Sean O'Hair 66-67-68-69, Patrick Cantlay 67-66-66-71, Michael Thompson 68-66-65-71
271 - Lucas Glover 68-68-68-67, Nate Lashley 72-68-66-65, Roger Sloan (CAN) 70-68-68-65, Daniel Berger 67-67-69-68, Scott Langley 70-65-66-70, Im Sung-jae (KOR) 71-65-64-71