Had the third round of the 45th Masters today been the final Sunday showdown, it would have lived in golf legend. This was prime stuff.

For years, we would have retold the tale of how Jack Nicklaus, leading at day's beginning by four shots, had, in the space of nine holes, seventh through 15th, gone from four strokes ahead to four shots behind Tom Watson. Finally, Watson ended the day one ahead.

From bearish confidence, Nicklaus had sunk, via two wet visits to Rae's Creek in the Amen Corner, to apparent wheels-off despondency. Watson, putting up six birdies, had suddenly taken the kind of lead that customarily makes him a links lock. Nobody runs better from the front than Watson; it is his metier.

Then, we might have whiled away an hour discussing the wave of shock that swept Augusta National as a grim Nicklaus birdied the 15th and 16th holes just as Watson took a blank-brain double bogey at the 17th, hitting a weak wedge into a trap, then three-putting from eight feet.

The four-shot Watson lead had, in perhaps 15 minutes, shrunk to none. Roars of delight, anguish and surpirse washed across the back nine.

Finally, we could have enjoyed the irony of Watson -- sitting in the press room flagellating himself for "putting like a 'hammer-mitts'" -- suddenly glancing up at television just in time to see Nicklaus miss a three-foot par putt on the 18th green to hand the lead back to him. "Ask Jack what 'hammer-mitts' means," Watson said, laughingly. "Nobody's immune to getting stone hands on these greens."

Instad of retelling these improbable and savory tales for decades, they will probably be forgotten with the morrow's sun, subsumed under the more pressing business of last-round drama.

"It's a wide-open golf tournament," said Watson, looking at a leaderboard that showed his 71-68-70 -- 209 total followed closely not only by Nicklaus (70-65-75 -- 210), but Australian Greg Norman (72 -- 211), John Mahaffey (69 -- 212), and Bruce Lietzke (71 -- 212). In a quality quartet at 213 were Ben Crenshaw (70), Peter Jacobsen (72), John Cook (72) and Lon Hinkle (74).

Whether or not Watson and Nicklaus pay too much attention to each other on Sunday -- although they will not play in the same twosome -- one of the seven fellows at 214, all major-championship winners, including Hubert Green (74), Jerry Pate (71), Lanny Wadkins (71), Johnny Miller (73) and David Graham (74), might fire the sort of last-day 66-or-less that has caused a Sunday rockus here so often.

Set aside all these rich future posibilities; this was a Saturday to remember. Both Nicklaus and Watson, the two finest players of the last 15 years, had this Masters in their hands and both relinquished it. Both left the Augusta National in moods of thorough self-disgust. Four-stroke leads in the Masters are the stuff of dreams and squandering them is the stuff of nightmare.

"Did you watch that exhibition today?" Watson said with distaste. "I had no touch whatsoever.Every first putt went three to five feet past the hole and I had to fight to save pars. It finally caught up with me at the 17th. I left some strokes out there today and I know it. The worst was misclubbing at the 17th when I had a 125-yard wedge -- an easy shot -- and misread the wind, knocked it in the trap and probably cost myself two shots."

Watson's self-reproach was nothing compared to Nicklaus'. After all, Watson could think back on birdies at Nos. 1, 3, 8, 13, 14 and 15, to cancel out his bogeys at Nos. 5 and 10.

Nicklaus was another story. As he walked off the 18th, his face looked so storm-cloud-filled that he might have bitten a mad dog had one crossed his path. Instead of his usual casual banter with the press, he hied to the practice range to beat balls in a black funk until dark.

"I wanted to get rid of my frustrations," said Nicklaus, who, in 87 previous Masters rounds, had only five worse scroes. "I want to leave both my tensions and my elation on the practice tee so neither one ever carries over into the next day."

He had plenty of sins to exorcise at dusk today.

"There are two cardinal rules of strategy in playing Augusta National," said Nicklaus. "Do not leave the ball right at either the 12th or the 13th because the ball will bounce down into the water. Those are the two worst penalties on the course. Today, I broke both rules. It was inexcusable. I doubt if I have ever hit the ball in the water at either the 12th or 13th when I was in contention in the Masters. I've done it when it didn't matter, but never when it did.

"Today, I guess I got greedy."

Or else he felt Watson's charging pressure.

Nicklaus, after a birdie at two and bogeys (ending his string of 39 pars or better) at the seventh and ninth, came at the Amen Corner with a two-shot lead over Watson. As his wind-wafted six-iron shot fluttered over Rae's Creek, Nicklaus' caddie coaxed, "Hurry."

"It's up, Willie. Don't worry," said Nicklaus. He was wrong. The ball bit the bank and backed into the drink. Just as Nicklaus finished his double bogey, Watson rang up a birdie at the 13th and took the lead.

Nicklaus may never say so, but his judgment and concentration wavered at the 13th. Instead of nailing his two-iron shot to the safe middle of the easy 465-yard par-5, he flirted with an eagle, landing his ball less than 10 feet from the pin. But that shot also danced on the sloped bank and dove into the creek. If Nicklaus does not win here, he surely will believe in his golfer's heart that those two misjudgements cost him four strokes and a sixth Masters green coat.

"My whole career I've had a tendency to throw away big leads in the middle of major championships. I know it. That's why it gripes me so much," said Nicklaus. "I backed up to the field in the middle stages of both the Open and PGA last year.The last time I won the Masters (in '75), I had a five-shot lead after two rounds (thanks to an identical 135 total to the scores he had here this year). In the third round, I shot 73 and Tom Weiskopf moved a stroke ahead of me, but I won (beating Weiskopf, 68 to 70).

"Well, I've done it that way before, so maybe I think I'll try it that way again."

That, however, was Weiskopf, a man on whom Nicklaus had the Indian sign. Watson is a different case; in the '77 Masters and '77 British Open, Watson showed that he could stand in the Nicklaus fire and answer with golf heat of his own.

Whatever Sunday brings, it will have great difficult matching the grand drama of this too-soon-forgotten Saturday at the Masters.