Mark Wilson's three-under-par 69 was enough to hold off Johnson Wagner and win the Humana Challenge by two shots in La Quinta.
Strong winds in southern California led to play being postponed on day three, meaning the field completed both their third and fourth rounds on Sunday.
Wilson posted a five-under 67 for his third round at the La Quinta Course, one of three venues needed to stage the $US 5.6m pro-am event.
Action shifted to the Palmer Course for the final 18 holes, with Wilson's closing 69 helping him to 24-under overall.
Wagner, a winner last week at the Sony Open in Hawaii, mounted the strongest challenge of the extended final day.
He carded a six-under 66 for his third round, and backed it up with a seven-under 65 later in the day.
But it was only good enough for 22-under, and a share of second place with two others.
John Mallinger turned in rounds of 68 and 66 respectively on Sunday, while Robert Garrigus posted a 68 and a 66, both men falling just short of Wilson's mark.
Jeff Maggert shot the low round of the day, with an eight-under 64 firing him 11 places up the leaderboard to outright fifth at 21-under.
And Australian John Senden was the best-placed non-American in the field, tied for sixth at 20-under alongside David Toms.
Wilson left it late to secure his fifth victory on the PGA Tour.
Resuming on the 17th hole of his third round, the 37-year-old made 10 pars and one bogey for his next 11 holes, and appeared in danger of being overhauled by the red hot Wagner.
But Wilson then produced a vital run of four birdies in the last eight holes of his fourth round, sealing his first title since last February's Phoenix Open.