ARDMORE, Pa. — We've seen this act before, so many times that Father's Day wouldn't be the same without watching Phil Mickelson find a way to lose the U.S. Open.

Someday he may write a book about it, though it would figure to be a tough sell. Misery and heartbreak usually are, even if Mickelson manages to hide both behind the big grin that never seems to go away.

Just how his latest drama will play out won't be known until sometime in the early evening hours Sunday at Merion Golf Club, the historic course that seems to be begging for a storybook ending to put alongside Ben Hogan's dramatic win in 1950 and the Grand Slam that Bobby Jones put his finishing touches on in 1930.

Hogan came back from a car wreck to win his Open here. That's fitting in a way because, should Mickelson somehow find a way to win in his 23rd Open he will have overcome a ton of wrecks of his own making.

He's had the lead in the Open with three holes left, and lost. He had the lead in another with two holes to go, and lost.

And, of course, he threw one of them away on the last hole when the only thing that seemed left to do was prepare his victory speech.

If careers were measured by blown opportunities, he'd be the leader in the clubhouse. Five times he's finished second in his nation's championship, the one tournament he wants so desperately to win and the one that has tormented him for most of his adult life.

Now he's got a one-shot lead with 18 holes to go for the first time in an Open. And now the fun really begins.

Heartwarming or heartbreaking. Either way, NBC has to be happy because it's going to be must-see TV.

"Let's go," Mickelson said after walking off the 18th green. "I can't wait to get back out playing."

With good reason, after a back nine Saturday that would have been impeccable had he not left a par putt on the last hole a half revolution short. On a golf course Tiger Woods and Rory McIlroy had no clue about solving, Mickelson was 2-under on the tough back side to finish up a round of 70 and take a one shot lead over Hunter Mahan and Charl Schwartzel.

He played safe but he played well, showing he's learned lessons from past Opens where his aggressiveness often got him in trouble. The Open is almost always a grind and that's especially true at Merion, where Mickelson is the only one who is under par for the week.

He's got three green jackets and a PGA Championship win so nerves on the final day of a major shouldn't be an issue. And it's hard to imagine anyone blowing by him on a course that yields birdies but is quick to punish mistakes.

Really all he has to do is shoot something par or under and the Open is his.

"I feel better equipped than I have ever felt heading into the final round of a U.S. Open," Mickelson said. "My ball striking 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."

Of course, he is Phil Mickelson so none of that may matter. Strange things tend to happen to him and around him, and there's no guarantee that in the heat of the moment his carefully thought out game plan won't be tossed aside like a broken tee.

That plan was crafted in practice sessions here a few weeks ago and short game work in the backyard complex of his San Diego area home. He studied it while flying overnight on his private jet for a 7:11 a.m. tee time Thursday after staying home to watch his daughter, Amanda, speak at her eighth grade graduation.

It's the same daughter who was born a day after the 1999 Open, where Mickelson finished second to Payne Stewart after leading by a shot with three to go.

The Open has always been a place where Mickelson seems to be in the midst of something besides golf. The last time he was the runner-up, in 2009 at Bethpage in New York, his wife Amy had just been diagnosed with breast cancer and his defeat was tempered by the reality of her illness and treatment.

He's now set up for either his greatest win since his Masters breakthrough in 2004 or the most bitter of all his many Open losses. He was honest enough to say that after his opening 67, noting how heartbreaking it would be if he were never to win this tournament.

But the stars all seem to be aligning for this one. Woods is not a factor, Schwartzel is the only other major winner in the top 10, and Mickelson has the lead all by himself.

Oh, yeah, it's also Father's Day for the father of three and it's his 43rd birthday, too.

"It's got the makings to be something special, but I still have to go out and perform and play some of my best golf," Mickelson said.

There are 18 holes and about five hours of work left to do, and a lot of trouble in between. But Mickelson is exuding the quiet confidence of someone who has figured it out, someone who knows what to do.

He understands that if you don't win your own national championship you will never be considered an all-time great. He knows that he won't have another 23 chances to get it done.

Mickelson has a chance to write his own ending to this story, and make it a best seller.

If he doesn't, this may go down as the one Open loss he'll never shake.

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Tim Dahlberg is a national sports columnist for The Associated Press. Write to him at tdahlberg@ap.org or http://twitter.com/timdahlberg