Going into the fourth game of the National Basketball Association's best-of-seven Eastern Conference semifinal playoff series, the score it: One-on-One Wizards 2 Traditional Team Playes 1.

The Philadelphia 76ers gained back the home-court advantage they had yielded in the first game in Philadelphia by spoiling the Boston Celtics' homecoming Friday night. 109-100, and afterward coach Gene Shue likened his Sixers to a football team that isoletes its best wide receiver on a vulnerable defensive back.

"We definitely have some skilled one-on-one players," said Shue, "so we try to take advantage of them, get them the ball in situations where they can function."

More of the same is expected in game No. 4 Sunday at Boston Garden (1:30 p.m., WTOP-TV-9).

The Celtics, winners of 13 NBA championships in 20 years, must win this game to have a realistic chance of defending their title. They will emphasize the traditional Celtic virtues of teamwork, balance and John Havlicek (75 points in three games).

Julius Erving enjoyed a routinely spectacular game Friday, performing "airs above the ground" worthy of the Lipizzan stallions and scoring a game high 27 points.

He is the top scorer of the series (90 points) and has gotten the Sixers off to quick starts each game, going to the hoop and scoring bunches of first-half points.

"We've been able to come right out and establish some control," said Shue. "That's what we'd like to keep doing."

While Erving has been consistently superb, the key for Philadelphia has been a sparkling and sparking performance for one or two of his colleagues.

Wednesday night at Phillie, it was guard Henry Bibby, with 22 points, six assists and the same sort of fine defensive work he has done throughout the series on Botson's Jo Jo White.

Friday night, it was guards Doug Collins (12 of 22 from the floor, 25 points) and Lloyd Free (nine of 13.22 points) who kept stuffing bones down the Celtics' throats, choking off every rally after the 76ers led by 15 in the first half.

Collins popped in a string of vital 15 to 18-footers at crucial points. But it was Free, who never looks at the basket before he shoots, then turns and bombs in off-balance 20 to 25-footers, who got the post-game attention.

His contribution, unlike that of skinny center Caldwell Jones under the boards, is one you can't help but notice.

"When the game was up for grabs, we had some fantastic shooting from Lloyd Free," said Shue."When you're watching, you say, 'What's he doing?' but that weird turnaround jumper from outside 20 feet is his shot."

"Gene just told me to clear the ball out and take whoever I can," said Free, relishing the spotlight. A radio man asked him if there was any way that he could be stopped. "Not that I know of," he said.

The 6-3, 185-pound, 23-year-old from Guilford, the Sixers' second-round pick in the 1975 draft as a hardship case, is a moody player. A few days ago, he said his jump shot had "gone to Europe." He was depressed at half-time. But his second-half shooting was a sure-fire cure for ennui.

"For two months, I haven't really played," Free said. "My body's been out there, but not me. I've been listening to the press tell me I'm a gunner. I'm no gunner. I'm a team player."

More accurately, he's the perfect Sixer, symbolic of this strange, fascinating-to-watch group of enormously talented individuals. For them, the spirit of '76 is not so much a chorus of "United We Stand" as five voices yelling loudly, one-on-one, "Don't Tread on Me."