Berger broke out of a five-way tie for second place to move ahead of Spieth, who had paced the field for two days, to earn his fourth PGA Tour victory. After grabbing a pair of eagles in his first three rounds of play, he grabbed two more on Sunday—hitting his fourth of the tournament on the 18th hole to clinch the victory that had already fallen well out of Spieth's hands.
This is the second week in a row that Spieth has had a late-tournament lead spoiled. He was tied for the top spot on the leaderboard heading into the final round of the Waste Management Phoenix Open before Brooks Koepka claimed the title. Last week, Spieth finished in a tie for fourth.
Maverick McNealy started the day in seventh place but used an eight-birdie round to put himself in contention to earn his first PGA tour victory, finishing at 16 under to hold a piece of the lead before Berger put it away.
Entering the final round, there was a five-way tie for second place, with Nate Lashley, Tom Hoge, Russell Knox, Patrick Cantlay and Berger all chasing Spieth from two strokes back. Spieth, whose last victory came at The Open Championship in 2017, sat at 13 under after commanding the leaderboard for two consecutive days.
On Sunday, he bogeyed twice on the front nine, and while he made up or it with a pair of birdies, Berger and Lashley climbed out of the second-place tie with spectacular play to open.
Berger hit an eagle and a two birdies to take over the lead.
And on No. 9, Lashley completed a run of three birdies in his last four holes on the front nine to take the outright lead at the turn.
A triple-bogey on No. 16 sealed the fate of Lashley.
Final Leaderboard and Prize Payouts
Winner: Daniel Berger (-18), $1,404,000
2: Maverick McNealy (-16); $850,200
T3: Patrick Cantlay, Jordan Spieth (-15); $460,200
T5: Paul Casey, Nate Lashley (-14); $301,275
T7: Charley Hoffman, Cameron Tringale, Max Homa, Jason Day, Russell Knox (-13); $228,930
12: Tom Hoge (-12), $181,350
13: Kevin Streelman (-11), $165,750
T14: Cameron Davis, Tom Lewis (-10); $146,255
Full leaderboard at PGATour.com.
Purse payouts via Golf Digest.