Steve Stricker moved up to number two in the world rankings after holding on to win the Northern Trust Open at the Riviera Country Club in Los Angeles.
The American fired a one-under-par 70 to edge out Luke Donald, who hit a final-round 66, by two shots.
Defending champion Phil Mickelson drops to third in the world rankings after closing with a 73 to finish back in 45th.
Stricker had led by six strokes after the third round and was forced to hang on in the closing stages as Donald set up a grandstand finish with a succession of birdies.
He said after his latest success: "It feels great, this means a lot. I remember where I was and look at where I am now, it doesn't get any better and I really appreciate it.
"It was hard. I aged a lot out there today and it was a grind from the get-go."
Dustin Johnson tied for third place on 13-under with fellow American JB Holmes, while another American, Paul Goydos, was fifth alongside compatriots Steve Marino and George McNeill, as well as Argentina's Andres Romero.