Los Angeles - Spain's Jon Rahm birdied the fourth playoff hole to beat Andrew Landry and capture his second PGA Tour title at the CareerBuilder Challenge in California.
Rahm, projected to rise one spot to number two in the world when the world rankings are updated on Monday, had five birdies in his bogey-free five-under 67 on the Stadium Course in La Quinta to seize the clubhouse lead on 22-under par 266.
But Landry, seeking a first PGA Tour title, rolled in an 11-foot birdie putt at the 72nd hole to cap a four-under 68 and force the playoff.
Both players parred the first three playoff holes - although each had birdie chances to win.
Rahm finally broke through when they returned to the 18th for the third time in the playoff. After finding the fairway at each of the first three playoff holes he was in the right rough, but still reached the green in two.
After he rolled in his birdie putt, Landry missed his from a similar distance on the other side of the hole.
"It's an amazing feeling ... to play the way I did and give myself a chance," said the 23-year-old Rahm, who has four victories worldwide in the past year.
"Obviously props to Andrew. To birdie 18 from the right rough, having to birdie it, that's a heck of an accomplishment.
"Either one of us would have been a deserving champion," added Rahm, who defends his first PGA Tour title at the Farmers Insurance Open at Torrey Pines starting on Thursday.
"I never thought I was going to be at this point in my life right now," he said, adding that it was "hard to believe" that he would move past three-time major winner Jordan Spieth into second place in the world rankings led by American Dustin Johnson.
Rahm, the highest ranked player in the field, opened the week in impressive style with a 10-under par 62.
He couldn't maintain that pace, and after a third-round 70 was two strokes behind rookie Austin Cook heading into the final round.
He was tied for the lead at 20-under after rolling in an 18-foot putt for his third birdie of the day at the 10th, and kept the chasing pack at bay with back-to-back birdies at 13 and 14 that moved him to 22-under.
Despite his impressive ball-striking, Rahm missed opportunities to give himself more of a cushion.
At the par-five 16th he followed up an impressive tee shot with a second shot that left him short of the green. His third shot gave him seven feet for a birdie but he missed that - unable to pick up strokes at any of the Stadium Course's three par-fives.
In the meantime, Landry was putting together a round that included five birdies and a bogey.
While Cook's bid for a second PGA Tour title was doomed by a pair of double-bogeys, a string of other players threatened the lead.
John Huh carded a six-under par 66 to head a group sharing third on 268 that also included Canadian Adam Hadwin (68) and American Martin Piller (70).
Kevin Chappell's 67 included four birdies in a row from the ninth through the 12th and put him on 269, tied with fellow American Scott Piercy who carded a 70.
Jason Kokrak birdied five straight holes on the back nine to get to 21-under but closed with a bogey and a double-bogey in a 69 that saw him tied on 18-under 270 with Sam Saunders (64) and Brandon Harkins (70).
Leading final-round scores on Sunday in the PGA Tour CareerBuilder Challenge, played on the La Quinta Country Club, Nicklaus Tournament Course and Stadium Course at La Quinta, California (x-won at fourth playoff hole, USA unless noted, par-72)
266 - x-Jon Rahm (ESP) 62-67-70-67, Andrew Landry 63-65-70-68
268 - John Huh 68-69-65-66, Adam Hadwin (CAN) 66-67-67-68, Martin Piller 64-67-67-70
269 - Kevin Chappell 71-64-67-67, Scott Piercy 68-65-66-70
270 - Sam Saunders 70-67-69-64, Brandon Harkins 64-68-68-70, Jason Kokrak 63-67-71-69
271 - Harris English 67-68-70-66, Seamus Power (IRL) 70-66-65-70, Jhonattan Vegas (VEN) 65-69-68-69
272 - Bud Cauley 67-68-71-66, Grayson Murray 65-68-67-72, Austin Cook 63-70-64-75
273 - Aaron Wise 64-69-72-68, Peter Uihlein 70-64-70-69, Andrew Putnam 69-66-69-69
274 - Brendan Steele 71-69-66-68, Beau Hossler 64-69-73-68, Zach Johnson 67-64-73-70, Ricky Barnes 71-65-68-70, Ryan Palmer 69-67-67-71, Brian Harman 65-68-70-71, Stewart Cink 68-69-65-72, Charles Howell 67-70-66-71, Nick Taylor (CAN) 68-71-69-66