ARDMORE, Pa. -- If a sleepless night is in store for Phil Mickelson, at least he can't blame it on a cross country flight. There should be plenty of time for rest and reflection, a long time to size up the situation and seize a moment that has eluded him for more than 20 years.
On his 43rd birthday, and Father's Day no less, Mickelson has a chance to snag the U.S. Open trophy that has eluded him -- sometimes painfully -- throughout his Hall of Fame career.
"It's got the makings to be something special, but I've still got to go out and perform," Mickelson said.
With an even-par 70 at treacherous Merion Golf Club on Saturday, Mickelson emerged as the only player under par through 54 holes of the 113th U.S. Open.
Hunter Mahan (69), Charl Schwartzel (69) and Steve Stricker (70) are a shot back at even-par 210. Justin Rose, Luke Donald and Billy Horschel -- the second-round co-leader with Mickelson -- are another stroke behind.
Of the top nine players on the leaderboard entering the final round, only Horschel is not ranked among the top 32 in the world.
"I love being in the thick of it," said Mickelson, who earlier this year captured his 41st PGA Tour title and last year was inducted into the World Golf Hall of Fame. "I've had opportunities in years past, and it has been so fun, even though it's been heartbreaking to come so close a number of times and let it slide.
"But I feel better equipped than I have ever felt heading into the final round of a U.S. Open. My ballstriking is better than it's ever been. My putting is better than it has been in years, and I feel very comfortable on this golf course. I love it."
Mickelson, ranked 10th in the world, has had his share of close calls at the U.S. Open, finishing second a record five times. He was runner-up to Payne Stewart in 1999 at Pinehurst, to Tiger Woods in 2002 at Bethpage Black, to Retief Goosen in 2004 at Shinnecock, to Geoff Ogilvy in 2006 at Winged Foot, and to Lucas Glover in 2009 at Bethpage Black.
Winged Foot was the most excruciating. Mickelson led by a stroke on the 72nd hole, hit a poor drive on the 18th, tried to do too much with his second shot and ended up making a double-bogey 6 to miss a playoff.
Afterward, he famously referred to himself as "an idiot" for letting the tournament slip away.
But as gut-wrenching as that loss was, the one in 1999 to Stewart remains fraught with irony.
At the time, Mickelson's wife, Amy, was pregnant with the couple's first child. Throughout the tournament, he insisted he would head home to California -- from North Carolina -- if she went into labor.
Stewart, who four months later would die in a plane crash, rolled in a 15-footer for par on the 72nd hole to beat Mickelson and avert an 18-hole playoff the next day -- which turned out to be when Mickelson's daughter, Amanda, was born.
Today, Amanda is a week away from her 14th birthday, that U.S. Open title still not part of her dad's trophy case. And it was Amanda whom Phil left Merion to visit earlier in the week, traveling all the way back to San Diego for her 8th-grade graduation on Wednesday night, then returning to Merion in the early-morning hours for his first-round tee time Thursday.
Mickelson, after rounds of 67-72-69, is in position to win his fifth major championship but has plenty of formidable challengers chasing.
Mahan, a five-time PGA Tour winner, is in his best position through 54 holes at a major championship. Schwartzel won the Masters two years ago with a four-birdie blast to the finish. And Stricker, at age 46, would become the oldest player to win his first major championship.
"It's the longest short course I've ever heard of," Stricker said of Merion, which has proven far more formidable than predicted, especially with so much rain to soften its fairways and greens.
"The U.S. Open seems to make you say, 'Don't make mistakes, don't make mistakes, don't make mistakes,' " three-time major winner Padraig Harrington said. "The U.S. Open makes you afraid to make mistakes."
Woods, the No. 1-ranked player in the world, matched his highest round as a pro at the U.S. Open, a 76 that left him 10 strokes behind. No. 2 Rory McIlroy shot 75 and is nine back.
Also chasing will be a couple of well-known Englishmen, Rose and Donald, each seeking his first major championship.
"When you look at Phil, he started winning majors around (age) 34 or 35, so I think I have some time on my side, luckily, in this game," said Donald, who two years ago won money titles on both the PGA and European tours. "Of course, that's my goal. I want to win majors. I got to No. 1 in the world and I've won a great amount of tournaments around the world, but I would dearly love to win one of these."
Mickelson, who birdied three holes on the back nine but failed to get up and down for par on the 520-yard, par-4 18th, visited Merion for two days last week, then decided on Monday in the midst of poor weather that he would return to San Diego to practice.
The plan all along had been to be there for Amanda's graduation, but skipping out on practice time at Merion seemed a curious decision. So far, it has not hurt at all, save for perhaps a few squandered opportunities on the greens.
"Given that I've had some past major championships now and some success here, I feel as well equipped as I could be heading into the final round, and I think it's going to be fun," Mickelson said.
If nothing else, the lead-up to the final round will be far less harried than Mickelson's start to the tournament. His final-round pairing with Mahan will not begin until 3:20 p.m. ET. He'll have breakfast, watch TV, maybe fret a bit, try to sleep in.
"But I don't sleep very well during majors," he said.
Given the circumstances, that is more than understandable.