LA QUINTA, Calif. — You couldn't blame the gallery at the Desert Classic presented by Workday on Sunday if they thought of Adam Long as nothing more than the other guy in the final pairing with Phil Mickelson and Adam Hadwin.

Mickelson, a Hall of Famer and immensely popular player in the desert, and Hadwin, a Canadian with plenty of support from valley snowbirds, drew huge cheers throughout the day.

But in the end, it was Long, playing just his sixth PGA Tour event, who outdueled the two crowd favorites to win his first PGA Tour title.

Long, a 31-year-old rookie, rolled in a 13-foot birdie putt on the final hole to cap a brilliant 7-under 65 on the Stadium Course at PGA West. That put him at 26-under 262 for the tournament, one shot ahead of Mickelson and Hadwin. Mickelson burned the low edge of the cup on the 18th with a 39-foot birdie attempt, while Hadwin was only able to get up and down from a bunker behind the green to make his par.

"I mean, I had nothing to lose. I was just out there having fun trying to hit fairways and greens and give myself looks for birdie and watching those guys," Long said. "It's fun to watch Phil play. I never have seen it up close like that, and it's a different game than mine, by a long stretch. But (I) just tried to focus on what I had to do and just was fortunate to make that putt there at the end."

Long's win was stunning not only because it was just his sixth start on the PGA Tour and fifth start in the 2018-19 year, but because he had missed the cut in his previous three events this season and finished tied for 63rd in the Safeway Open in his only other start this year.

Mickelson, a two-time winner in the desert, stumbled to a final-round 69 but caught Hadwin and Long with a birdie on the 16th hole. Hadwin finished with a 67 but played the final seven holes in six pars and one bogey. It was Hadwin's fourth straight year in the top six in the tournament and second time as the runner-up.

Long, who has two rounds of 63 during the week at La Quinta Country Club and the Nicklaus Tournament Course, made an early statement with birdies on the first two holes. He added a birdie on the ninth hole, but was still just 22-under, behind Hadwin at 25 under and Mickelson at 23 under.

Mickelson had started his day with a three-putt bogey on the first hole and he never improved much on the greens.

"I had a terrible putting day, one of the worst I can recall in a while," Mickelson said. "Started right on the first hole with a little 4-footer uphill and 3-putting that green there.

"And I missed a bunch of short ones on the front and some birdie opportunities, but it felt awful with the putter," Mickelson said. "I hit a lot of good shots today though but just couldn't get the ball to go in the hole."

Hadwin, looking for the breakthrough desert win, was flawless for 11 holes, with six birdies to take a three-shot lead over Mickelson at 26-under par. But Hadwin's game started to fray a bit, with the Canadian star missing a birdie putt on the 12th, missing the green on the way to a bogey at the 13th and missing another birdie chance on the 15th. It was another heartbreaking loss for Hadwin and the large Canadian population in the desert that pledges its loyalty to him from the first tee shot.

"It's like playing back in Canada, to be honest with you. Canadian Open, there's always that added pressure," Hadwin said. "You want to win in front of them. It would have been a special moment if I could have pulled it off but there's always next year, I guess."

Long made birdies on the 12th, 14th and 15th to tie Hadwin at 25 under. But Hadwin and Long both flubbed chips on the par-5 16th, perhaps the only time during the week Long look like he was playing in his sixth PGA Tour event. Hadwin and Long made pars while Mickelson missed a 15-foot eagle putt that would have given him the lead outright.

When the trio parred the 18th hole, it set up the drama of the closing hole. Long missedthe fairway but recovered with a strong approach. Mickelson hit the fairway put couldn't get his iron close to the pin in the back of the green. Hadwin bounced through the green and into the bunker.

When Long's putt went in the hole, ther cheers from the gallery that have been for Mickelson and Hadwin before now belong the Duke University graduate.

"It's pretty exciting. I mean I was, I wasn't even in the field for next week in San Diego, I was an alternate," Long said. "So we'll take it one week at a time, but, yeah, it's exciting and changes I want to say my life. But it changes my career for sure."