Philadelphia's Maurice Cheeks was at the foul line, his team trailing by two points with 29 seconds to play. Boston's M.L. Carr walked up behind Cheeks, tapped him and said, "Don't choke."

Cheeks said later it didn't bother him, but he missed the first of his two shots and that eventually proved to be the Celtics came from way back once again to overtake the 76ers, 91-90, and win their NBA Eastern Conference championship series, four to three.

With only one day of rest, the Celtics begin the NBA championship series against Houston Tuesday in Boston.

The game-winning basket was scored on a 12-foot bank shot by Larry Bird, the man who made so many big plays for the Celtics today and throughout the series, with 63 seconds left.

After Cheeks made only one of his two free throws, the Celtics got possession and ran the 24-second clock down to one second before Carr put up a shot from the left corner. It missed, but when Bobby Jones got the rebound, one second remained in the game.

The 76ers called timeout to set a play, but with only one second left, it was a prayer. Jones threw the ball inbounds from midcourt, attempting a lob pass to Erving, positioned under the basket. It was too high, bouncing off the top of the backboard and down to Cedric Maxwell, who touched the ball. That touch started the clock, and time ran out.

The Celtics trailed by 11 points with 6:48 left in the third quarter and seven points with 5:23 remaining in the fourth. They gave up one point the rest of the way, on Cheeks' free throw. And that is how Boston became only the fourth team in NBA history to win a seven-game series after trailing, 3-1.

That defense, really a collapsing zone, prevented Philadelphia from getting inside and foiled the 76ers' offensive rebounding efforts, enabling the Celtics to come back in this remarkable series. They trailed by 11 points late in the fifth game and 17 in the sixth, relying on defense more than offense to bail them out.

It was no different today.

The Sixers had none possessions in the final five minutes and scored only one point. They missed six shots and had four passed stolen, two, by Bird, who once again played a solid game. He scored 23 points and had 11 rebounds, five assists, five steals and two blocked shots in 43 minutes.

The Sixers squandered an 11-point lead in the third quarter. Boston ended the third period with three straight points and opened the fourth with eigaht in a row to turn a 75-68 deficit into 79-75 lead with 9:40 to play.

But with Julius Erving leading the way, they fought back.

An Erving 17-footer and an Erving scoop tied the score at 79-79. Boston's Kevin McHale made one free throw to slow the 76ers down momentarily, but the visitors came back with eight unanswered points, four by Erving, to silence the 15,320 At Boston Garden and give Philadelphia an 87-80 lead with 6:10 left.

Tiny Archibald made two free throws and Erving scored after getting an offensive rebound with 5:23 to go to keep Philadelphia's lead at seven. Then the Celtic defense came alive.

"We stopped playing defense with our hands and started playing it with our feet and our bodies," Fitch said.

Philadelphia went to Erving virtually every time down the floor. Cedric Maxwell Hounded him every step and whenever Erving got by him, another Celtilc, or two, or three, was there to harass the Doctor.

Two straight times down the floor, Erving got up in the air with nothing to do and threw the ball away as the Celtics got closer, converting every turnover into points. "No team has every stopped the Doctor with one man and we didn't today," said Fitch.

Bird tied the score on two free throws after Erving fouled him with 2:51 left.

The Sixers had three chances to score on their next possession, but Erving missed twice and Lionel Hollins missed as Bird got the rebound.

The tension mounted as Parish missed a jumper, but the Celtics got the ball back when the rebound went off Hollins' foot and out of bounds. Archibald missed for the Celtics, with that rebound going out of bounds off Maxwell.

The 76ers went to Dawkins. He got the ball down low, but Archibald was under him and Parish on top of him. He shot an offbalance eight-footer that missed. Dawkins was knocked to the floor, but no foul was called.

"I took the ball to the hoop with three guys on me and got knocked down," Dawkins said. "I didn't fall down and I didn't get a call. What kind of garbage is that?"

Bird came up with the rebound in a crowd and took off on a one-on-two fast break. He pulled up 12 feet from the basket and banked it in off the glass for a 91-89 Boston lead with 1:03 left.

Erving got caught in the air with nothing to do again on Philadelphia's next possession and three an errant 25-foot pass to no one that Carr intercepted.

Hollins knocked the ball away from Gerald Henderson of Henderson's dribble, however, and Cheeks picked it up and raced toward the basket. Henderson caught him and fouled him, preventing Cheeks from making the layup.