In the end, what had looked for the better part of three quarters like a Boston Celtic romp turned into the noisiest, wildest, most harrowing of escapes for the men in green, and bedlam reigned in Boston Garden.

When the last drops of emotion and controversy were wrung out, and a frantic seven-minute surge by the late-erupting Philadelphia 76ers was spent like a hurricane blowing itself out over the Atlantic, the Celtics owned today's fourth game of the National Basketball Association's Eastern Conference semifinal playoff series, 124-119.

On a nostalgic day when the Celtics trotted out their heritage at halftime, commemorating the first of the 13 NBA titles they have won over the last 20 years, they needed all the imperviousness to pressure their dynasty has represented to even the series at two games apiece, going back to Philadelphia Wednesday night.

On a "must-win" day when the Celtics finally got off to an early lead and were able to play their own game, they saw a 22-point lead (77-55 and 79-57) get hacked down to a single point (116-115) with 1:55 left to play, and then had to break a furious full-court press to escape with the victory.

On a day when Dave Cowens played an incredible first half (10 for 10 from the floor, three for three from the foul line, 13 rebounds), when captain John Havlicek came up with the key plays he has been making for the last hundred years or so, when Jo Jo White got hot when he had to, the biggest Celtic hero was an unlikely one: Fred Saunders.

The 6-7 forward, whom the Celts dug off the Phoenix scrap heap as a free agent last spring, was in the game because starters Charlie Scott and Curtis Rowe and sixth-man Sidney Wicks had fouled out in that frenetic fourth quarter, in which the 76ers came back like a band of cold-hearted snipers conspiring to break Boston's heart.

With 1:34 left, and the Sixers' deficit down to one after a spurt in which they outscored the suddenly disarrayed Celts, 23-10, Saunders hit a running righthanded book from eight feet out in the lane over Julius (Dr. J) Erving.

Thirty-five seconds later - after Doug Collins (37 points), whose shooting alone had kept the 76ers in the ball game earlier, had lost the ball out of bounds - Saunders found White all alone under the hoop with a pass. The Celts' most consistent scorer (26 points today) made the layup for a 120-115 lead, and the gush of green blood had been clotted.

During those final minutes, when tempers and feelings were lighting up like a pinball machine, the ancient Garden atop Boston's North Station shook with the deafening concerto for voices and stomping feet that has been likened to the sound of a subway train as heard through a stethoscope.

Nevertheless, Saunders, the 25-year-old who was recently voted Boston's "unsung hero" of 1976-77, responded in the best Celtic playoff tradition.

"The man at the point had been dropping off to double-team Cowens," he said of his critical hoop. "We were trying to get the ball to Dave, but when they sagged off I had the shot. I had a half-step on the Doctor, and thought, 'Ho, ho ho.' But I respect his leap, so I went with the hook.

"Pressure? I try not to think about it. There's nobody pushing down on your head. Some people think the playoffs are another reason, but it's the same ball, the same players. You stay as calm as you can and do your job."

"A runnin' hook - I've never seen him use that shot before," said Erving, who awakened in the fourth quarter and finished with 23 points, leading the uprising with Lloyd Free (12 points, 10 in the fourth quarter), Collins and George McGinnis (27 points).

"I don't know if he (Saunders) used that all year, but he broke it out at the right time."

Havlicek, Mr. Clutch for 17 years, had 15 assists, 11 in the first half, and 12 points. But the man who most came to play the Celtics was Cowens, the Big Red center of the Big Green Machine, who went all 48 minutes for the first time this year and got 37 points (16-of-24 from the floor) and 21 rebounds.

After the game, Celtics coach Tom Heinsohn ranted about the decisions of the rookie officials who are being used during the strike of regular NBA referees (Joe Crawford and Richard Jackson today).

Sixer coach Gene Shue filed a preliminary protest of the game, contending that the Celtics should have been allowed only three-sounds instead of 10 to get the ball across half-court after White, trapped, had bounced the ball out of bounds off McGinnis' leg with nine second remaining and the score 122-119. White had taken the inbounds pass, a play that consumed seven seconds.

The Sixers have 48 hours to file a formal protest, after plunking down $500 for the preliminary. But NBA Rule 4, Section VI-B, explicitly proves Shue wrong.

"A team must bring the ball across the center line within 10 seconds," it states. "If, however, the defensive player causes the ball to go out of bounds in the backcourt, the offensive team will still be allowed 10 seconds to bring the ball across the center line."