Lefty has always done things a little differently.
No one can argue with his methods now because they're working. Mickelson arrived at Winged Foot as the winner of the last two majors, and with a victory at the U.S. Open he can join Tiger Woods as the only players in the last 50 years to win three straight.
So where was he Wednesday on the final day of practice at Winged Foot?
Having studied Winged Foot close to a dozen times during the last two months, and wanting to escape the carnival atmosphere that has gripped U.S. majors in recent years, Mickelson headed to New Jersey for a leisurely round on a course that holds great memories.
It was at Baltusrol where his major streak began 10 months ago, when he hit a flop shot out of the mangled rough to tap-in range for birdie and a one-shot victory at the PGA Championship. Then came the Masters, where Mickelson quickly separated himself from a world-class leaderboard.
Suddenly, the guy who couldn't win a major has a chance to win three in a row.
"I'm not trying to win three, I'm just trying to win one," Mickelson said. "I know I can play well in this tournament, even though it doesn't necessarily fit my perception of how I've played with the thick rough. I still have had some success here, and all I'm trying to do is be successful on this one golf course at this one event."
It starts this morning at Winged Foot, a vicious course because of its multiple layers of rough that frame narrow fairways, cavernous bunkers and greens with severe slopes.
The USGA was up to its old tricks when it made the tee times for the first two rounds. Mickelson, who tees off at 7:55 a.m. on the 10th tee, will be playing with Tim Clark and Thomas Bjorn, who finished second to him at the last two majors.
At stake for Mickelson is a slice of history that looked so improbable three years ago.
Since the Masters began in 1934, players have won consecutive majors only 13 times. Woods is the only one to have won at least three straight majors played; Ben Hogan did not play in the 1953 PGA Championship because it was held the same week as qualifying for the British Open, which he went on to win.
Woods figures to be one player capable of stopping Mickelson's momentum.
The world's No. 1 player in also on a roll, even though that has been overlooked this week with so much attention on Woods playing for the first time since his father died. Woods has not finished worse than a tie for fourth in his last five majors, winning the Masters and British Open last year.
He hasn't played since a poor final round with the putter Sunday at the Masters, where those close to him believe he was trying too hard to win another green jacket before his father died. Woods has looked sharp this week, especially off the tee and controlling the distance of his irons, which is crucial because of the greens.
As for that Woods-Mickelson rivalry?
Woods mentioned other guys who have challenged him in the last 10 years, from Mickelson to Ernie Els, from David Duval to Vijay Singh, and even Sergio Garcia on a slow news day.
"As long as I can be part of that conversation, it's never a bad thing," Woods said.
Woods has gone about his preparations differently from Mickelson. He played one practice round at Winged Foot two weeks ago and 36 holes since arriving this week -- nine holes Monday afternoon, 18 holes Tuesday, the back nine Wednesday morning.
Mickelson has played so much that he might be an honorary member at Winged Foot.
There have been Mickelson sightings in Westchester County the last two months -- restaurants, coffee shops, you name it -- as he pops in and out to study Winged Foot, to figure out where he can and cannot afford to miss a shot, always looking for an edge.
"I can't recall frequenting a coffee shop. I don't drink coffee," Mickelson said. "But there's been a couple of pizza joints and ice cream joints that have seen me. I've been here a decent amount. I feel as though I know the course as well as I can. I may know where I want the ball to do. I know how the putts break. But I still have to hit them, and that's the toughest part."
Mickelson estimates he has been to Winged Foot nine or 10 times since the Masters -- he even came over Sunday morning before his final round at the Barclays Classic -- which is so different from everyone else, but also intriguing to his peers.
"He's obviously taking it quite seriously," Ernie Els said. "There's a lot going on out there. You're guessing where they're going to put the flags, so you hit putts everywhere. You try to hit every shot that you think you might need on each and every hole. And to do that in a practice round is tough. To do it away from the tournament ... that's real preparation."
That has been Mickelson's M.O at the majors for the better part of two years.
He spends up to eight hours on one practice round well in advance of the tournament, sticking a dozen tees in the greens to aim at potential hole locations, working his away around the green to place various shots out of the rough and sand. He has put so much thought into the majors that he carried two drivers at the Masters, and has added an extra wedge for Winged Foot.
Now he has to make it pay off.