It also happened to be his 43rd birthday.
And just in case he forgot, fans serenaded him with a chorus of "Happy Birthday" when Mickelson showed up at the practice range before his afternoon tee time. His round began with a shot seen many times this week a drive that landed in thick rough.
The U.S. Open inched its way toward history Sunday on the take-your-time course at Merion Golf Club, where high rough and hard greens have made for slow rounds, and the threat of rain made a Monday finish a realistic scenario even without a playoff.
There was Mickelson, hoping to finally win the championship after finishing runner-up a record five times. There was Steve Stricker, trying to win his first major. Both are famously proud papas: Mickelson flew cross-country on the eve of the tournament after watching his daughter graduate from eighth grade, and Stricker has been playing less on the PGA Tour to spend more time with his family.
There was Hunter Mahan, who is not quite a dad. On a day when seemingly every golfer was talking about the special day on Twitter, Mahan chimed in with: "Happy Fathers Day to everyone! A couple months before I get to join the club!"
Also in the mix were Luke Donald and Justin Rose, each hoping to become the first Englishman to win the trophy since Tony Jacklin in 1970.
And don't forget Billy Horschel. He wouldn't let you if you tried. He tweeted a photo of himself wearing what he called his "highly anticipated" and "highly controversial" octopus-print golf pants.
Mickelson's score was 1-under after the third round, one ahead of Mahan, Stricker and Charl Schwartzel and two ahead of Donald, Rose and Horschel. All were taking aim at the red wicker baskets that sit atop the pins at Merion, all trying to follow Olin Dutra, Ben Hogan, Lee Trevino and David Graham as U.S. Open champions who conquered the tough little course in the Philadelphia suburbs.
While the leaders were waiting to tee off, Tiger Woods went through the motions of extending his majors drought into a sixth year. It was an unfamiliar sight to see the world's No. 1 golfer teeing off on a Sunday more than three hours before the top pairing, but he was 10 strokes off the lead after a third-round 76 that matched his worst U.S. Open round as a pro.
Woods wore his usual Sunday red shirt, but it didn't keep him from quickly achieving a dubious double out of bounds and a 3-putt on the same hole. That made for a triple-bogey 8 at No. 2. He was 13 over for the tournament midway through the back nine.
Sunday was five years to the day since Woods won the U.S. Open at Torrey Pines. His running tally of majors wins is stuck on 14, four shy of Jack Nicklaus' record.
Hopes for a Grand Slam were also being officially dashed. Masters champion Adam Scott began the day 11 strokes behind Mickelson and made three bogeys on the front nine.
Meanwhile, Shawn Stefani found a unique way to solve Merion: Hit the ball in the rough and get a hole-in-one. His 4-iron at the 213-yard, par-3 17th landed left of the green, bounced down the slope and meandered its way some 50 feet across the green and into the hole.
Stefani nearly jumped out of his skin. Then he kissed the spot where the ball landed.
"We're in Philly," he said. "There's some great fans up here, and I know they can be tough on you and they can love you forever. So I'm sure they appreciated me going to the ground and kissing it."
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