On Sunday in the Boston Garden, the Celtics demolished the New York Knicks in the first game of the finals in the Eastern Conference playoffs. In outcome, the victory echoed the Celts' first game 134-108 devastation of the Knicks in last year's playoffs.

Last year, however, the Knicks fought back and smashed the Celtics by more than 20 points in the second game and went on to win the series in seven games. This year, the Celts should be able to stave off any similar Knick surge.

The key to the Celts' success on Sunday was coach Tommy Heinsohn's strategic substitution in the second quarter. Heinsohn sent Paul Silas in for Don Chaney and moved John Havlicek to guard along with Jo Jo White, creating a serious mismatch with Knicks guards Walt Frazier and Earl Monroe.

Awesome Combination

Heinsohn discovered the awesome combination in the sixth and final game against the Buffalo Braves. Trailing by seven points early in the third quarter, Heinsohn made the crucial substitution pitting Havlicek and White against Buffalo's Randy Smith and Ernie DiGregorio. By the end of the quarter, the Celtics sported an 87-82 lead as White and Havlicek collected eight points each and Havlicek grabbed 12 rebounds.

On Sunday, Havlicek moved to guard early in the second quarter with the score knotted at 23 and quickly hit a 20-foot jumper over Frazier to push the Celts into a lead that they never relinquished.

Havlicek repeatedly victimized Frazier and his eventual substitute Monroe with his size and strength, taking the ball deep inside and either passing it off to Dave Cowens for a left hook or putting the ball up himself.

Occasionally, he picked his defender off and created a one-on-one match against New York's center John Giandelli. Havlicek continually out-faked the gangly big man, drawing the foul, and converting at the charity line, where he was a perfect seven for seven.

The strategy paid off, but the Celts can't go with it throughout their series with the Knicks. If they do, the Knicks will press the Celtics all over the court. Havlicek plays awesome basketball, but his ball-handling is no match for Frazier's quick hands. As ex-Kinck Dave Stallworth once said, "That man is so fast that he could steal the hubcaps off a moving car."

Undoubtedly, the Celts will rely primarily on their run-and-gun offense which piloted them to first place in the Atlantic Division the past three years. But the Celtics' running offense depends on their ability to dominate the boards. In every game of both the Celts-Braves and Knicks-Bullets series, the team that dominated the rebounding won the game.

Unexpected Problems

The Braves gave the Celts unexpected problems because Jim McMillian, Gar Heard and Bob McAdoo continually ripped rebounds away from their opponents' outstretched hands.

The Knicks, however, can only boast of Dave DeBusschere as a consistently good rebounder. In the final game against the Bullets, Knicks' Gianelli outrebounded Elvin Hayes 15-12, but Hayes dominated the series, 98-41.

On Sunday, Dave Cowens outrebounded Gianelli, 13-3, even though he left the game with 3:48 remaining in the third quarter and never returned.

The Knicks managed to stay close in the early going because Frazier grabbed five rebounds in the first quarter, but once Havlicek moved to guard, Frazier had other things to worry about.

In the second half, Knick coach Red Holzman used Willis Reed in an attempt to keep Cowens away from the boards. The strategy backfired, however, as Cowens concentrated on offense and poured in four hooks over the gimpy Reed.

Add to these factors Paul Westphal's knack for slicing through the Knick's faltering defense for a few quick baskets, and the Celts look like sure winners over the fading Knicks.

On Sunday, the Knicks, who are the best perimeter-shooting team in basketball, shot a lowly 33 per cent. Frazier was high man for the Knicks with 16 points, and Monroe and Bradley could only combine for a mere ten points.

If the Knicks get hot, they will shut down the Celtics' fast-breaking offense and force them into a slow, methodical patterned style of play which the Knicks roving, switching defense is apt to take advantage of.

The second game of the series is at Madison Square Garden tonight at 9 p.m. If the Knicks take this one, the series will probably go seven games; if they lose, it's all over.