The 2018 event was won by Ted Potter Jr., who missed the cut this year when he was unable to bounce back after shooting an 82 in the first round and finished the three-day stretch at 12-over par.
"All I'm focused on is the Masters".
"As much as I would like to finish, it's probably a good thing", Mickelson said.
Phil Mickelson is closing in on three decades on the PGA Tour and a half-century on Earth, and he still feels his best golf is good enough. "Paul's wonderful. He made me relax".
He also won the Pro-Am with Don Colleran, the chief sales officer for FedEx.
Mickelson's longest putt for par was 4 feet.
On Monday morning, he had a change of heart and said he thanked Casey for standing his ground. In second is Scott Stallings, who sits at -15 and has finished his tournament. Mickelson was on the 17th tee, shaking his head when he heard the siren to stop play.
Phil Mickelson does not believe heading to this year's U.S. Open with a win at Pebble Beach already in the bag increases his chances of completing a long-awaited Grand Slam.
It also would be his first victory on American soil since the Phoenix Open six years ago. Casey's only hope was for Mickelson to make a mistake, and there was little chance of that. He surrendered a four-shot lead previous year at the Travelers Championship, where Bubba Watson closed with a 63.
Greens quickly were covered by the tiny white pellets, and workers went from using squeegees for excess water to power blowers to remove the hail. They were waiting to tee off when sunshine gave way to a hail storm that pounded the golf course as players ducked under umbrellas.
Pebble Beach was so soft that balls were plugging in the fairway when they landed.
Casey bogeyed the 11th after failing to get up and down from the rough, giving Mickelson the outright advantage, with the Englishman then missing a six-footer to save par at the next to fall two behind.
'Sometimes I get in my own bubble, ' Mickelson said. And it is where he will turn 49 on the final day of the 2019 U.S. Open.
Australia's Jason Day finished tied fourth after his four-under-par 68 came in one of the last groups to finish before sunset on Sunday evening before darkness fell. A terrible tee-shot was followed by a chip that failed to find the green and a third that wasn't much better and after a fast start, which had seen him birdie the first two holes and three of the first five, and following a run of 11 straight pars, the 38-year-old Aussie missed his bogey attempt and tapped in for a double-bogey five.