(CNN) -- Phil Mickelson saw a five-shot lead disappear before recovering with two late birdies to successfully defend the Northern Trust Open in Los Angeles.
Mickelson holds the Northern Trust Open trophy aloft for a second successive year.
Overnight leader Mickelson eagled the opening hole at Riviera Country Club but saw his advantage slip away with five bogeys in 13 holes.
Fellow American Steve Stricker briefly led before Mickelson birdied the 16th and 17th to edge him out by a stroke.
The left-hander's one-over-par 72 for a 15-under 269 was enough for his 35th career victory on the PGA Tour and first of the 2009 season.
Stricker signed for six birdies in a four-under 67 to claim second -- with veteran Fred Couples (69), South Korea's KJ Choi (69) and Argentina's Andres Romero (70) third at 13 under.
JB Holmes (68), England's Luke Donald (68), Mark Calcavecchia (69) and South Africa's Rory Sabbatini (70) finished tied for sixth at 12 under.
World number five Mickelson, who trailed Stricker by two shots with three holes to play, picked out his approach to the 16th as the shot which turned around his fortunes.
"It was a nine iron from 152," Mickelson told Press Association.
"It was playing 152 with the downhill. I think the actual yardage was a little longer. It was a key shot for me, because I knew I was two back. I knew 18 was a very tough birdie hole, so I had to birdie 16 and 17 to get even with Stricker.
"I birdied 16, and after I hit my best drive of the week on 17, I saw that he had bogeyed 18. So now birdie on 17 would give me the lead. But it goes back to that birdie putt on 16. Without that, I'm still fighting just for a playoff."
After holding a five-foot birdie putt on the 16th, Mickelson drained a birdie putt from similar range at 17 before safely parring the final whole for a welcome victory after a shaky start to the season.
He had led by four shots overnight after a brilliant third round 62.