Fifteen years ago, when he was just a teen-ager and Jack Nicklaus was already established as the king of golf, Tom Watson would find a way, on Sunday mornings, to be the first dew-sweeping player on the Pebble Beach Golf Links.

"I'd drive down here from Stanford (University) and tee it up at 7 a.m., when I'd have the whole course to myself," said Watson this evening. "Honestly, I did fantasize about coming down the stretch, head to head with Jack Nicklaus in the U.S. Open.

"Then, I'd get to the last couple of holes and say, 'You've gotta play these one under par to win the Open.' Of course, I'd always play 'em two over. And I'd say, 'You have a long way to go, kid.' "

Tom Watson has had to come a long, slow, arduous way. But today, all his fantasies, plus one piece of magic so outlandish that even a boy playing at sunrise would never dream it, became reality. And history.

With one shot that will live in the retelling as long as golf is played, Watson wiped away--like a Pacific fog along the cliffs evaporating with the morning sun--the last blemish on his great and growing record.

Years from now, it will probably be forgotten that Watson won this 82nd U.S. Open by two shots over Nicklaus in a breath-stopping back-nine duel. In time, the details of this misty, Monterey evening may fade--even the trenchant fact that, with Nicklaus and his 69--284 total already in the clubhouse, Watson finished birdie-birdie on the 71st and 72nd holes to slash his way out of a tie with the fabled Golden Bear.

In 19th-hole lore, only a few will recall that Watson's pilgrimage to his first Open title was carved out with a week of creditable work (72-72-68-70) for a six-under-par total of 282. To be sure, no one will recall that Bill Rogers (74), Bobby Clampett (70) and Dan Pohl (70) tied for third at 286.

In the end, only one moment--one shot that epitomizes both Watson and his game--will last. Already, Watson calls it, "The shot . . . the greatest shot of my life, the most meaningful."

It's that one swing, and no other, that prompted Nicklaus to grab Watson in a fraternal bear hug as he stepped off the final green and tell him, "You son of a . . . you're something else. I'm really proud of you."

Naturally, Watson remembers the embrace a bit differently: "Jack said, 'I'm gonna beat you, you little SOB, if it takes me the rest of my life.' "

So, for the moment, we will forget how Watson began the day tied for the lead with Rogers. We will pass over the jubilation that swept this seaside links as the dormant Nicklaus birdied five straight holes on the front nine--the third through seventh--to forge, momentarily, into a one-shot lead.

We will negligently dash past the details of how two bogeys by Nicklaus--one perhaps abetted by a former U.S. president--plus a cross-country birdie by Watson, pushed the 32-year-old redhead back into the lead by two shots. And, finally, we will gloss over Nicklaus' classy birdie at the 15th and Watson's wild drive and bogey at the 16th that deadlocked the pair for the lead one final time.

The scene thus set, we must return to the one moment from this Open that will outlast and, unfortunately, diminish all others. Outlined against the blue-gray sky of Carmel Bay, Watson stands locked in ankle-deep rough beside the 17th green. In trying for a daring birdie--hitting a two-iron into the breeze at the 209-yard par-3, Watson has, instead, put himself in just the predicament for which Jack Neville built this course in 1919.

No shot in golf is a better test of nerves, experience and touch than the "grass explosion" from high, unforgiving U.S. Open rough to a pin on a glass-slick green that is only 18 feet away.

Watching on TV, Nicklaus, who was going for a record fifth Open title and 20th major, says he thought, "There's no way in the world he can get up-and-down from there (for par). Even if he has a good lie, you couldn't drop the ball straight down out of your hand on that green and keep it from going less than 10 feet past the pin. I figured, 'Now, he's going to have to birdie the last hole just to tie me and get into a playoff (on Monday)."

Watson's opinion was different. "I'm not trying to get this close," he recalled telling his caddie. "I'm going to make it."

Why shouldn't he have thought so? Perhaps no man since Arnold Palmer in his prime has so consistently willed the ball into the hole from ludicrously improper places. On the 10th, Watson was on a cliff side amidst wildflowers; he hacked to the fringe 24 feet away and sank his Texas-wedge shot to save par. On the 11th, he sank a 22-footer from the fringe for a birdie. And at the 14th, he was in the frog hair again, and holed out from 35 feet. As Nicklaus put it, "Yes, yes, I heard about all those shots. Just another tap-in for Tom."

With this preternatural confidence, which is his trademark, Watson stepped into the weeds by the 17th quickly and, opening the face of his sand wedge, "sliced across the ball and slid the edge of the club under it. It was a good lie, with the ball hanging in the middle of the grass. If it had been down, I'd have had no shot . . .

"As soon as it landed on the green, I knew it was in," said Watson, whose whole face was alive with hunger as the ball trickled and broke--a full foot and a half from left to right.

"When it went in the hole, I about jumped in the Pacific Ocean," said Watson with a laugh. He ran at least 20 yards around the edge of the green, his putter over his head in victory and his feet carrying him he knew not where. Then, commanding himself, Watson spun and pointed at his caddie and yelled, "Told ya!"

"He was chokin', chokin' bad," Watson said with a grin. "He couldn't utter anything."

Neither could Nicklaus. "When he makes that, the golf tournament's history . . . I've had it happen before, but I didn't think it was going to happen again. But it did . . . How would I evaluate that shot? One of the worst that ever happened to me. Right up there with (Lee) Trevino's (chip-in) at Muirfield (on the 71st hole of the '72 British Open)."

An almost certain bogey that probably would have lost his Open and branded Watson a gagger had been turned, in a twinkling, into one of the most gloriously improbable Open-winning birdies in history.

Had Watson merely parred the 17th, he would have had to birdie the 18th to win. And nobody has ever birdied the 72nd hole of the Open to win. As it was, Watson's downhill 18-foot birdie on the last hole was a wonderful crescendo for a day full of tremulously roiling drums. But, had Watson needed to make it to win, it might have been a tougher proposition.

Watson's playing partner, Rogers, said of that soft shot into history, "He couldn't have hit a better shot if he'd dropped down a hundred balls."

"Try about a thousand," said Nicklaus drolly.

Told of Nicklaus' odds-making, Watson--as superb a greenside magician as Nicklaus has always been bear-pawed--said, "Let's go out and do it. I might make some money."

Watson faced up to every sort of Open pressure today. "I was on pins and needles all day."

Watson woke up nervous, then calmed himself by reading two newspapers "front to back. Ask me anything about the earthquake in El Salvador or the budget problems." His swing was loosey-goosey all day--he missed only one fairway, but his putting was nervous and cold on the front nine, especially when he missed a two-foot birdie putt at the seventh.

Perhaps Watson was unhinged by all those bear tracks he had to walk through. As he trudged through the third through seven, all he heard was buzzing talk about how Nicklaus, after a shoddy bogey-par start, had been knocking down flags for five consecutive holes. By the time Nicklaus had made two-foot tap-ins for birdie at the fifth and sixth, he was tied for the lead. And when he sank a 12-foot curler at the gorgeous seventh to take the lead, his caddie--son Jack Jr.--jumped nearly two feet in the air and began applauding.

Nicklaus misclubbed himself at the over-a-gorge eighth and was lucky to make bogey from a hanging lie on the edge of a precipice. That, however, won't be the bogey that haunts him. At the 11th, tied for the lead, he had a flat, slightly downhill 18-foot birdie putt that he slid four feet past and missed coming back. What could have accounted for his only mental lapse of the day?

No one will ever know for sure, but lovers of anecdote might enjoy the fact that former president Gerald Ford, a notorious three-putter, walked down from a course-side house and stood conspicuously by the 11th green as Nicklaus three-putted. Ford then came forward to shake Nicklaus' hand and exchange pleasantries at the 12th tee--an intrusion into serious work that no normal citizen would, presumably, have dared to attempt. Call it the Presidential Bogey or Jerry's Whammy.

In the gathering dusk around America's most lustrously atmospheric links, Watson was aglow with pride and vindication. Asked, teasingly, "Why can't you win the PGA?" he said, 'Up 'till now, it's been, why couldn't Sam Snead and I win the Open. Now, it'll be, why can't Arnold Palmer and I win the PGA? Well, I'll stay here all night and talk about it."

Time and again, Watson had to return, as he will have the pleasure of returning for the rest of his life, to the Impossible Shot.

"I had no alternative," Watson said, finally, with his best freckled, gap-toothed smile. "For you, it's impossible."

But not for this country's overdue and deserving U.S. Open champion.