Woods was changing his shoes and chatting with a few reporters last year when Mickelson walked into the room. Before long, two of the best players in golf starting lobbing school-yard challenges at each other, everything from racquetball to tennis, from basketball to swimming. Weary of where this was going, Woods ended the banter with a playful shot at Mickelson's physique.
'Tell you what,' Woods told him. 'I'll take you on in anything where you have to run.'
Mickelson smiled, but went silent, one of those rare times he was at a loss for a comeback.
When and where their rivalry began is hard to pinpoint. They have been linked so often that Mickelson was surprised to hear the first time he and Woods played the same tournament was the 1993 Nissan Open. Woods received an exemption as a 17-year-old amateur and missed the cut, Mickelson was in his first full season on the PGA TOUR and tied for 19th.
They never have met in a playoff, as Jack Nicklaus and Arnold Palmer did at the 1962 U.S. Open. And for the last several years, Mickelson merely has been part of the rotation of rivals to Woods, sharing time with Ernie Els or David Duval or Vijay Singh.
That's no longer the case.
Woods-Mickelson figures to be the main event at the U.S. Open when it starts Thursday at Winged Foot.
They are Nos. 1-2 in the world ranking. Their peers say they have the most raw talent in the game. They have won four of the last five majors, with Mickelson capturing the last two. And for the first time since Woods' record victory in the '97 Masters, he might not be the favorite at a major championship.
'There's clearly two guys out here doing the thing, doing the damage,' Paul Azinger said. 'I think Phil Mickelson is the best shotmaker on tour right now. I think he's the most confident player in the world. And I think he's the man to beat.'
How Woods will perform is a mystery.
He has been coping with the May 3 death of his father, and Woods has not played since the Masters. The nine-week break is the longest of his career.
'It's a matter of getting sharp -- not mentally sharp, but golf sharp,' John Cook said. 'It will be interesting to see how Winged Foot goes for Tiger.'
No matter how much emphasis is on Woods and Mickelson, the first priority is getting a handle on Winged Foot. This will be the fifth U.S. Open held on the classic Tillinghast design in Mamaroneck, N.Y., a course known for greens that slope severely toward the front, cavernous bunkers, tree-lined fairways and deep rough.
'I just earned a ticket to hell,' Mark Brooks said after making it through a U.S. Open qualifier.
The USGA has introduced graduated rough, where the grass grows taller the farther it gets from the fairway. Big hitters have been swinging from the heels on the PGA Tour with little regard for where it goes, finding it just as easy to hit wedge out of the rough as a 6-iron from the middle of the fairway.
Winged Foot might not allow for that. The rough is so deep that Mickelson said there might be a thousand golf balls buried in there, hit by members who couldn't find them.
'I'm going to make a prediction that somebody hits the wrong ball in the rough,' Mickelson said.
Mickelson and Woods ran into each other at Winged Foot a few weeks ago, in the clubhouse when each took a break from practice, and later as they crossed paths on the fairway.
But meeting in majors, or any tournament, is rare.
Woods held off Mickelson at Bethpage Black four years ago in the U.S. Open, although they were separated by one group. The one time they did play together in the final round at a major was at the 2001 Masters, when Woods held him off to capture his fourth consecutive major. In regular PGA Tour events, there was that sizzling duel at Doral, which Woods won with a 6-foot par on the last hole.
But don't get the idea Mickelson is always on the wrong end.
It was Lefty who stopped Woods' winning streak at six by beating him in the 2000 Buick Invitational. Woods went four years without losing a 54-hole lead on the PGA Tour until Mickelson beat him that year at the Tour Championship, denying Woods a 10th victory.
And lately, in the majors, Mickelson is the one holding the trophy.
'There have been times where I've come in under the radar not having played that well, not being considered a favorite,' Mickelson said. 'But I think that's going to be unlikely for the U.S. Open.'
What makes a rivalry is not so much head-to-head meetings, rather the record. Nicklaus and Palmer are famous for that playoff at Oakmont in '62, but their rivalry was compelling because of their different personalities, they way they were perceived by the public and how they swapped green jackets. Either Nicklaus or Palmer won the Masters five straight years.
Woods, like Nicklaus, has an incomparable record among his peers, with 48 victories and 10 majors. Mickelson, like Palmer, rarely goes anywhere without his ears ringing from so much applause, especially when a major goes to New York.
And they have had their moments in the press.
Mickelson irritated Woods three years ago when he told a magazine that Woods uses 'inferior equipment.' He meant to say Woods uses outdated technology, such as a 43-inch shaft made of steel, and Woods eventually caught up with the times. Mickelson apologized to Woods before the '03 Buick Invitational, and Woods wound up winning by four shots while playing with Lefty in the final group.
Brad Faxon filled out that threesome. He was called 'Switzerland' that day.
But it was Mickelson who was among the first to publicly say Woods was singularly responsible for a spike in PGA Tour purses. And when Mickelson's winless streak in the majors reached 0-for-40, it was Woods who rallied to his defense by saying that Mickelson had so much talent that it was a matter of time, and that Mickelson was the best wedge player on tour.
Their relationship often is misunderstood, which is not to suggest they're best friends. It didn't help when they both played poorly while paired together for the first time in the Ryder Cup two years ago. They rarely spoke, and stood some 20 yards apart on the first tee of their opening match.
Nicklaus saw a different side to their relationship last year at the Presidents Cup.
'The first day I get there, Tiger and Phil said, 'Hey, let's go play some pingpong.' Two guys are playing, having a good time, laughing, kidding each other,' Nicklaus said. 'Now, is that bad blood? I'm sure they're competitors. Absolutely, they want to beat each other. But you know, they still spend time together and enjoy each other's company.'
The year Woods turned pro, Mickelson was one of the biggest attractions in golf. His fourth victory that year came at the World Series of Golf, the same week Woods was winning his third straight U.S. Amateur. Players gathered around the TV in the locker room at Firestone to watch the U.S. Amateur, wondering what to make of this guy.
'When he turned pro, you still weren't sure how good he was going to be,' Mickelson said. 'And when he won in the first few weeks, that's when everyone realized he was going to be an incredible player.'
He passed Mickelson within three years. Now, Mickelson is doing his best to catch up.