Howell had gone 4 1/2 years and nine runner-up finishes since his lone PGA Tour victory. At almost every turn Sunday, he was confronted with so many of his past failures _ all the putts he missed, the 10th hole at Riviera that denied him victory in 2003, a chip that cost him last month in Honolulu.
He erased those memories with three clutch pars in the playoff, the last one on a solid chip to 3 feet and a putt that felt like a mile. Howell raised his head and closed his eyes in utter relief, and his voice cracked as he spoke about the winning putt.
"I said, 'God, if this is the time, then let's knock this in,'" Howell said. "And fortunately, it was."
Four shots down at the turn, Howell closed with a 6-under 65 and scrambled in the longest playoff at Riviera in 25 years until Mickelson blinked first, missing a 10-foot par try on the par-3 14th.
"I had every chance on the back nine to create some separation and not give anyone a chance," said Mickelson, who twice missed putts inside 4 feet and closed with a 68. "I felt like I had the tournament in my grasp and let it go."
Coming off a five-shot victory at Pebble Beach where he tied a tournament scoring record, Mickelson was poised to get in the Riviera record books until he stumbled along the back nine. He missed a 2-foot par putt on the 13th, then misplayed a 4-foot birdie putt on the 16th hole to fall into a share of the lead.
Needing a par to win, he came up short on the 18th and hit a pedestrian chip to 18 feet and took bogey.
"I had the tournament in control," Mickelson said. "It happens. It's part of the game."
They finished at 16-under 268.
Ernie Els (67), Jim Furyk (67) and Robert Allenby (68) tied for third, three shots out of the playoff.
Els and Allenby both had chances to catch Mickelson along the back nine of a mostly sunny afternoon, but the Big Easy was tripped up by three bogeys, while Allenby fell back with a three-putt from 60 feet on the fringe at the 15th.
Howell earned $936,000 and is atop the PGA Tour money list for the first time in his career.
"It's been a long time," Howell said. "I've always said Riviera was my favorite golf course other than Augusta National."
Now he can make plans for the Masters, the major about 5 miles down the road from where he was raised. Howell likely will move into the top 25 in the world ranking, all but assuring his spot in the field.
And he got that bitter playoff loss out of his memory.
Four years ago, Howell lost a three-shot lead in the final round at Riviera, then hit a spectacular bunker shot on the 10th only to miss an 5-foot birdie putt and lose to Mike Weir.
He was on the ropes at No. 10 in the playoff, his ball on the cart path some 100 feet left of the hole. His sand wedge off the concrete clipped a tree and dropped down, and with Mickelson in the neck of the green on the 314-yard hole, Howell looked doomed.
But he played a pitch with perfect pace to 3 feet, Mickelson played away from the flag to 20 feet and both left with par.
Howell's putting was never better. He curled in an 8-footer for par on the 18th in regulation that kept the heat on Mickelson, and holed a 6-footer for par on No. 18 to extend the playoff.
Mickelson squandered a couple of huge breaks that looked like they would carry him to victory.
His flop shot on the 10th in regulation was heading into the back bunker when a tuft of kikuya grass, cut like a Marine's flat top, stopped it on the very edge. Instead of scrambling for par from a deep bunker, he used a utility club to knock in a 20-footer for birdie and lead by two shots.
Then on the 12th, his approach bounced off Humphrey Bogart's tree _ te sycamore left of the green where the actor used to watch the tournament _ and caromed onto the green instead of down into a ravine. Those breaks were wasted, however, by missing two short putts and failing to make par on the final hole.
"I'll look back and see a lot of opportunities," Mickelson said. "On a good note, it's better to get those out of the way early with the upcoming majors."
Howell trailed by as many as five shots early in the final round and was still four behind with eight holes remaining, seemingly playing for second place. But he pecked away, and his fortunes turned quickly when he knocked in a 30-foot birdie on the 16th, then two-putted from the fringe for birdie on the 17th.
In the group behind, Mickelson's momentum again was slowed by a short putt when his 2-footer went 270 degrees around the hole.
Tied for the lead, Mickelson took it right back with a big drive that left him only a hybrid from 255 yards into 25 feet on No. 17 for a two-putt birdie. And he was presumably in good shape in the left rough on the 18th.
Howell kept his hopes alive by curling in his 8-foot par putt to post at 16 under, forcing Mickelson to make par to win.
Mickelson hit 8-iron from 204 yards, trying to get the ball to the front of the green and let it roll to the back, but it failed to clear a mound leading to the 18th green, and his chip came out flat to 18 feet. The putt never had a chance, sending both players back to the 18th for a playoff that lasted three holes and produced a huge win for Howell.
Asked which was more meaningful, the Nissan Open or '02 at Kingsmill, the 27-year-old didn't hesitate.
"This one," he said. "Because of the five-year gap between them. It's been a long, long time since I won a title."