Three years ago on Easter Sunday, Craig Stadler became so distraught with the game of golf and his exasperating place in it that he sat in the azaleas behind the 12th hole here at Augusta National and cried.

Soon, on another Easter Sunday, the emotional, vulnerable Stadler will have a chance to replace that embarrassment with the memory of a Masters triumph.

Lots of people think Stadler won the Masters today when he shot 31 on the back nine for a 67-211 total and a three-shot lead after three rounds. After starting the round with a double bogey 7 on the second hole, the Walrus rolled in nearly 100 feet worth of birdie putts on the final three holes to break a tie with Jerry Pate (67-214) and Seve Ballesteros (68-214).

Stadler knows better than to be fooled by the temporary euphoria of jumping around the 16th, 17th and 18th greens as improbable putts of 15, 50 and 30 feet crept across these slick, bent-grass greens and found their way into the cup.

He sees the glamorous thoroughbreds poised just over his shoulder, waiting for him to falter--Tom Weiskopf (68) and Ray Floyd (69) at 215, Tom Watson (70) and Bob Gilder (66, the tournament's best round) at 216, and even Jack Nicklaus (71) in a trio at 217 that included Curtis Strange (73), who was tied with Stadler for the second-round lead, and Dan Pohl (67), whose back-to-back eagles at Nos. 13 and 14 started a stretch in which he played four holes in six under par.

"I'll always remember it," Stadler said at dusk, recalling his trip through Amen Corner in '79 when he went from a tie for the lead to off the leader board in just three awful holes. "Maybe I learned what the hell not to do out there."

Those behind Stadler know his Tour reputation: fast starter, shaky finisher. Already this year the hot-tempered Stadler has had last-day leads at four events--Tucson, the Crosby, Doral and Bay Hill. He won only Tucson. At the Crosby, Stadler led by five shots with nine to play.

In just the last four years, brutal collapses by third-round leaders have been the rule here. In '78, Hubert Green had a three-shot lead and lost. In '79, Ed Sneed was up by five to start the last day, and three ahead with three holes to play, and lost in a playoff. And in '80, Ballesteros saw an amazing 10-shot lead with nine holes to play shrink to two shots with five holes left.

"The lead is a lot of pressure," said the spectacularly erratic Ballesteros, who had three bogeys, five birdies and a three-foot tap-in eagle at the 15th after a 298-yard drive and a stone dead four-iron shot. "It's nice to be in the dark and come out (into the light). I think it is more easy to win from behind than to be leading."

But didn't he win from the lead?

"I was seven shots in front (after three rounds), not three shots," grinned Ballesteros. "And I was 10 shots ahead and I still almost . . .you know what happened."

"The nerves ought to be very taut tomorrow," said Watson, who battled the tee-ball hooks all day, righted himself with a birdie chip-in at the 14th, then finished with birdies at the 15th and 18th. "Craig's in the driver's seat, but there's more pressure on him . . . If he makes a few mistakes . . . "

"With wind (predicted 20 miles per hour), it'll be a good test," said Weiskopf, who has redeemed himself after shooting 85-79 here in '80 (including a 13 at the 12th), then didn't even qualify in '81. "It's easy to shoot 72, 73, 74 if you play just a little bad, and it's easy to shoot 66, 67, 68 if you play well."

Perhaps the most truthful and graceless of Stadler's pursuers was the lean and hungry Pate. As he watched a live television shot of Stadler's transcontinental birdie at the 17th, Pate narrowed his eyes and said with feeling, "Good . . . I hope he gets way on out there."

The better to draw the spotlight. The better to feel the pressure and sleep with it. The better to be the hunted on Easter.

The only really kind word for Stadler came from Nicklaus, who walked off the course grinning and giving the thumbs-up sign after concluding a tormenting day with back-to-back 20-foot birdies at the 17th and 18th. "When I walked off the course, I felt like I was going to be (just) three shots behind. Then I walk in here and see (Stadler's) birdie-birdie-birdie (on the score board). . . I guess his day is arriving."

This was the sort of day for which the Masters was created. The crisp, sunny, windless spring weather was glorious. The rain-softened greens held iron shots as though they were arrows. And the greens committee took mercy, for one day, with lenient pin positions and no double-cutting of the greens. As a result, waves of birdie, and eagle, roars took the place of the snickering and shivering of Thursday and Friday.

Gilder dazzled even himself with a nine-birdie 66 in which his iron shots were so perfect that only one of his birdies came from more than 10 feet. "What we (pros) can do astounds me at times," shrugged Gilder. "You can shoot nothin' if you're playin' good."

Gilder's low round of the tournament was, however, outshone by a pair of 67s by Pohl and amateur Jodie Mudd, whose score was the lowest ever by a first-time amateur.

The 21-year-old Mudd, who like his brother Eddie has been national public links champion, told how his father, who died last spring, had had "one dream, and that was for one of his sons to play in the Masters.

"So," said Mudd, on the verge of losing his self-control, "he knows I played in the Masters, but he really doesn't."

All in all, the stage could not have been better set for Sunday's finale as five of the most wonderfully expressive, temperamental extroverts in a sport of methodical introverts have stormed to the top.

When the furnace-faced Stadler wasn't glaring like a man ready to eat his putter after missing a five-foot birdie at the 15th, then Ballesteros was pulling his visor down over his face in self-mockery after a drive into the woods. When Floyd, who slashed a low, hooking shot out of the rough at the 18th to within a yard for a tap-in birdie, wasn't winking roguishly to the crowd, then Pate, the man who jumps in lakes, was taking a woman's bag out of the line of his backswing and, for some unknown reason, placing it in the fairway, which he had missed.

And when it wasn't one of these bona fide contenders causing excitement, it was Weiskopf, four times runner-up here and now an aging sentimental favorite, who was finally learning how to smile and draw cheers rather than growl and grump until fans rooted for him to fail.

Now the Georgia winds are gradually picking up at nightfall. A smidgen of light rain may be on the way. The Augusta elders have plotted out the most diabolical "A" pin placements for Sunday. The mowers have been set at one-eighth of an inch with orders to double-cut to the roots. The Amen Corner, beautiful as it is cruel, waits. The Masters is Craig Stadler's to have and hold. If he can.