Mickelson was at his best on a course he loves. That was start of a five-hole stretch when Mickelson made three birdies and Paul Casey had two bogeys, taking Lefty from two behind to three ahead.
A rain delay and bad light forced Mickelson and Casey to return on Monday and the 48-year-old retained his three-shot lead to seal glory at the site of this year's U.S. Open - the only major he is yet to win and has finished as runner-up in six times.
"I thanked Paul this morning for letting us finish today", he said of the delayed finish.
For much of the final day, Ormsby's only serious danger had looked to be pre-event [130.0] shot, Brad Kennedy, and the veteran Sydneysider hit a low of [2.1] himself as the pair duelled it out on the back nine but it was all change late on when [1000.0] chance, David Law, rallied superbly after calling a penalty on himself on the ninth. "Sometimes I get in my little bubble and don't see the bigger picture".
Casey also closed Monday's play with a birdie putt at 18 to finish alone in second at 16 under. Casey and FedEx executive Don Colleran had a one-shot lead in the pro-am. Check in for highlights from every tournament plus player interviews, player profiles, tournament previews, swing analysis and all the greatest shots and incredible moments.
At least Phil Mickelson didn't break his own record for the longest event in PGA Tour history.
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Law trailed Ormsby by fully five strokes after his penalty and he still trailed by three with just three to play but he birdied the par four 16th, parred the tricky par three 17th and then did this with his second to the par five 18th!
"It has been a treat this week", Casey said. He played the final 26 holes in cold, damp and windy weather without a bogey.
"We've got two tough holes left and I don't want to jump the gun and get past that", Mickelson said.
The fourth and final day of action was delayed when hail began coming down, as the Pebble Beach Pro-Am Twitter account showed.
His first one also was a Monday finish, when players returned in August - more than six months later - to finish the third round of the weather-plagued tournament to make it official.
And while the fairway lines already have been cut much tighter at Pebble, the conditions were so soft that balls plugged in the fairway when they landed and greens easily held shots even from the rough.
Mickelson lives for the moment.