Bruce Lietzke said he was "in a trance" this afternoon as he birdied four consecutive holes on the testing back nine of the Augusta National Golf Club to assume the first-round lead in the 43rd Masters Tournament.

A trance. It must have been, for Lietzke-a 27-year-old who did not better 70 in his only previous Masters appearance, in 1977-did not make a bogey until the final hole of what he called "a very easy, stroll-in-the-park type round."

Lietzke's five-under-par 67, which could easily have been closer to the course record of 64 if his crosshanded putting stoke had been more assured, gave him a one-stroke lead over pre-tournament favorite Tom Watson and three others.

Watson seemed on the verge of spontaneous combustion on a muggy but gorgeous Georgia afternoon. He was five under par after 14 holes and thinking "eagle" on the 15th, but he hit a poor six-iron approach into a pond and wound up giving a stroke back to par instead of picking of two.

Watson, the leading money-winner on the PGA Tour for the third consecutive year, finished the first round over Augusta's superbly conditioned, 7,040-yard course tied at 68 with Leonard Thompson, Joe Inman and Ed Speed.

Five-time champion Jack Nicklaus, who played well but did not make a putt of more than five feet on greens made extra-treacherous by tough pin placements, headed a group of five players two strokes back.

One of those five was Andy Bean. Among the other favorities, Gary Player shot 71, Severiano Ballesteros had 72 and Tom Weiskopf, Lanny Wadkins, Ben Crenshaw and Lee Trevino had 73.

When Lietzke stepped to the 18th tee, he was six under par - the biggest red number of the day on the scoreboards that are almost as plentiful as azaleas at Augusta.

His "trance," a serene state of mind into which no negative thoughts were allowed to intrude, had ended moments earlier on the wickedly contoured 17th green, where he missed an eminently makeable five-foot putt that would have given him a fifth consecutive bridie.

"I missed that putt, and I was standing on the 18th tee, shaking my head," the pleasant University of Houston grad said later, recreating his sense of satisfaction at his afternoon's handiwork.

"I knew how I stood. I knew I was six under par. I said, 'Now how did I get six under? So I thought back and said, 'Yeh, I birdied 13, 14, 15, 16. Yep, that's four in a row, and it could have been five."

Golf, this splendidly masochistic game of self-inflicted psychological torture, should always seem so simple. But it seldom is, and Lietzke, back down to earth, promptly hit a three-wood too far left, under a television tower on the fairway of the 420-yard finishing role known as "Holly."

"I had been driving well, I hadn't missed fairway all day, but I decided to go with a three-wood to stay away from the fairway bunkers on the left. That was a bad choice of clubs," he said.

"I got a free-drop from under the tower, but I hit a poor seven-iron to the back and left of the green, and had a very difficult chip shot. I left it above the hole, which was the last place I wanted to be, and missed a very touchy five-footer.

"My round was pretty uneventful until then. But I think if I hadn't missed the birdie putt on 17 and broken my trance, I possibly would have birdied 18 as well, knowing the way things were going on inside of me."

It is a measure of the sweet things going on inside Lietzke that he could consider "unevenful" his string of birdies on the par-5 13th (putt and tapin from 20 feet), par-4 14th (18-foot putt, his best of the day), par-5 15th (lipped out his eagle putt from 25 feet) and par-3 16th (14-foot putt, after nervelessly hitting a six-iron over Rae's Creek).

All this after routinely getting around "Amen Corner," the celebrated beginning of the back nine where so many players-starting with Lanny Wadkins at mid-morning, when the skies were still gray-splashed themselves out of contention.

"It was just a trancy type of thing that I've been through before," Lietzke said. "It's nice. I just choose my club, line up the shot and pull the trigger. It's a great feeling, one I wish I could have all the time."

He is realistic, however. He has not played well since winning at Tucson in February. He has recovered fully from a pulled stomach muscle that sidelined him for two weeks into introduced flaws to his swing, but he knows he must do more work on the practice range if he is to have a chance at the champion's green jacket come Sunday.

"This round was very surprising, and confidence-building, but I don't have enough confidence in my swing right now to win the tournament. I don't know where the shots came from today," he said.

Perhaps they were heaven-sent compensation for past disappointment, for Lietzke admits he was upset about not getting a Masters invitation last year, even though he finished fifth on the PGA Tour earnings list in 1977.

He hadn't won a tournament, though, so he couldn't come back to Augusta-where he tied for 28th in 1977-until he won the Canadian Open last year.

Watson, the 1977 champion, finished in a three-way tie for second last year after scoring an eagle at the 13th hole on the final round, only to give the tournament away by three-putting from six feet on 14.

Today Watson-his strawberry-blond hair fluttering in the breeze and his complexion reddening in the humid sunshine, adding more color to a landscape already bright with flowering trees and shrubs-had six birdies and two bogeys on the first 12 holes.

At 13, he drove between two trees on the right, but he drilled a three-iron shot from a good lie to within eight feet of the pin. He settled for a birdie when he left his eagle putt on the lip.

He hit a magnificent drive on 15, and was thinking "eagle" again as he selected a six-iron for his shot over one pond to a green guarded by bunkers and more water behind.

"I had 188 yards to the front of the green, by my calculations, but it was straight downwind," Watson said of his club selection as he looked toward the vast amphitheater of people around the 15th green.

"It (the wind) got pretty calm as I was about to hit, but I decided to stay with the six-iron anyway. A five-iron probably would have been right, but I wanted to get close enough for a 3."

"Ugh!" came the collective groan of the gallery as his shot hit the far bank of the pond and rolled into the dyed, blue-green water.

"That was my only really bad shot . . . probably a two-stroke swing, at least," Watson said.

After that, no one else got to five under and challenged Lietzke. The course was ripe for scoring. The fairways were immaculately groomed and the greens holding, but the pin placement kept a lid on.

"If you put the ball where you should, you were looking at tough downhill putts all day," Nicklaus said.

Inman, who had no bogeys, agreed.

"Even though the surfaces weren't glass-fast, the pins were so far back that on at least seven holes, you could easily have putted yourself right off the green" Inman said. "It was not a course to take a run at today."

Unless of course you were in a trance. CAPTION: Pictures 1 through 3, Gary Player watches birdie drop, left; Lanny Wadkins, Center, and Bruce Lietzke celebrate birds of their own. UPI/AP