South Korea's Si Woo Kim outlasted America's Patrick Cantlay to take The American Express title by one shot in La Quinta.
After heading into Sunday's final round sharing the top spot on the leaderboard with Americans Max Homa and Tony Finau, Kim saved his best for last, clinching his third PGA Tour victory with eight birdies and a bogey-free round of 64.
However he was pushed the whole way by Cantlay, who surged from 13th to second with a new course-record score of 11-under 61.
Cantlay started his day by birdieing the second and only got better from there, picking up 10 more shots to complete his best career round as a pro.
Finau shot a four-under 68 to finish third, while Homa dropped to equal-21st with a horror round of 76.
Paul Casey finished equal-eighth to lead the English contingent, with Scotland's Russell Knox closing out his tournament with a one-over 73 to finish equal-16th.