Mickelson was desperate for success on his hometown course
Phil Mickelson's US Open challenge came crashing down when he notched up a quadruple-bogey nine on the 13th hole on a difficult day at Torrey Pines.
The world number two and local favourite saw three pitch shots run back down a steep slope in front of the green on the 614-yard par five.
Mickelson birdied the last for a 76 but ended nine over for the tournament.
"Unfortunately it happens. It sucks, but it happens," said Mickelson, 37, who has yet to win a US Open.
The three-time major champion is tied with Sam Snead for the most US Open runner-up finishes without a victory, with four.
"I'm certainly disappointed that I'm not in the mix right now," he added. "That was the goal. So I'm going to come out tomorrow and enjoy my final round."
This is something I wanted a lot and I just didn't play well this week
Mickelson, who lives at nearby Rancho Santa Fe, had high hopes of US Open success on the South Course at Torrey Pines, where he grew up playing golf and has won three Buick Invitationals on the PGA Tour.
"This is something I wanted a lot and I just didn't play well this week," Mickelson said. "It was really one hole that hurt the round. Otherwise I was one over for the day and just played OK."
The left-hander had opted to leave out a driver for the first two rounds and instead carried five wedges.
And he blamed the addition of a driver on Saturday for his aberration from around 75 yards on the 13th, which ended with a three-putt.
"Hitting driver just threw me off. I hadn't done it," he said.
"It's just a great pin that will entice guys to get a little bit close, and certainly that's what I did on my first shot.
"The other two were just poor. But the first shot had a good chance of being close and making birdie and it just came back down.
"I hit lob wedge the first time and then I hit the 64 [degree] the second and third and fourth. But I had perfect lies, which is probably why I tried to get a little cute. I could hit a good shot with the lie I had."