This was not the Celtics team that we have come to know over the past few weeks. The execution was sloppy at times, the defense substandard at others.

But still there was a chance, improbable as it may have seemed, to beat the Magic and advance to the NBA finals. With the score tied, 86-86, and 16 seconds left, Paul Pierce dribbled up the court with the chance to make one more game-winner.

This is what Doc Rivers wanted — Pierce with the ball — and so he felt there was no need to call a timeout and gather his team. In retrospect, maybe he should have called one, because on a night when the Celtics could do very little right offensively, they forgot the most important element of a Pierce isolation play. That is, it’s hard to be isolated when everyone is running toward the ball.

“It was supposed to be Paul at the top with a pick and roll with Ray [Allen], and then the floor was supposed to be flat and spaced,” Rivers said. “Half our team was standing next to Paul.”

Pierce lost the handle as he went to make his move through all that traffic and couldn’t even get a shot at the basket, which led to overtime and a 96-92 loss as Jameer Nelson drained two huge 3-pointers. (Recap.)

Now their series lead is down to 3-1 with two of the remaining three potential games in Orlando.

“It was amazing how bad we were execution-wise and still had a chance to win that game,” Rivers said. “That was amazing to me.”

Pierce took the blame for the final shot, saying, “Just pretty much screwed it up. Pretty much turned the ball over and that’s all it is. Couldn’t get the final shot.”

Pierce had very little for which to apologize. He took almost a third of the team’s shots and scored more than a third of the team’s points with 32 in almost 47 minutes of basketball. But that’s the way these things go, and considering everything that had gone wrong for the Celtics, it was amazing that they had a chance to win it in regulation.

They are still in control of this series, and as we know, they have no fear about winning games in other people’s buildings.

“There’s no need to panic,” Allen said. “We like the position we’re in. It’s just always a lesson, in humility. We have to take care of the small things, and they’ll add up to what we ultimately want.”

They can start with the smallest player on the Magic, because Jameer Nelson played like the biggest man on the court.

JAMEER DIDN’T CALL ‘BANK’

Throughout the last six minutes of the regulation and on into the overtime, you got the feeling that one big shot was going to decide things. As it turned out, the big shot came from Nelson, who rather improbably banked in a 3-pointer in overtime that gave the Magic the lead for good.

“I didn’t call the bank shot, but it went in,” Nelson said. “I kind of misjudged where I was at. [It] was the first time I was wide open and it kind of shocked me.”

Dwight Howard scored 32 points and had 16 rebounds, a monster game by anyone’s standards, but the key for the Magic was Nelson, who has been the player that has most concerned the Celtics since the series got underway.

The Magic ran him off multiple picks in the high pick and roll, crunching Rajon Rondo at every opportunity, and that allowed Nelson to get into the paint and do damage. The Celtics play defense with aggression and the only way to counter it is to meet it head on, which was Nelson’s plan all along.

“The first three games I was worried about swinging the ball and getting everyone involved,” Nelson said. “But my thing is, if I get in the paint and be aggressive, that’s how I get everybody involved.”

On a night when Vince Carter was again rendered invisible — 1-for-9, three points — and Rashard Lewis again failed to register much of an impact, it fell on Nelson to deliver his team a victory.

“I thought he dominated the game,” Rivers said. “This entire game. He went wherever he wanted on the floor.”

The Magic have talked a lot about not letting this series define them and what they’ve been able to put together over the last few years and Nelson took that to heart, which should surprise no one who has ever been around him.

In Chester, Pa., on the outskirts of Philly, where they take their basketball only slightly more seriously than breathing, Nelson is a revered and sainted figure. His college coach, Phil Martelli, loves to tell the story about watching him dominate a tight state playoff game without taking a single shot, and of course he nearly took the St. Joe’s Hawks to the Final Four his senior season.

He has been a winner his whole basketball-playing life and it had to burn him the way his team played in Game 3. He is, next to Howard, the most important player on the Magic and while his star is often eclipsed by the likes of Howard, Carter and Lewis, he is the heart, soul and brains of the operation.

“We just wanted to come out tonight and prove to ourselves that it wasn’t going to be any letdowns and come out fighting,” Nelson said. “Just come out fighting.”

His counterpart in this series, Rondo, has been the transcendent player of the postseason, but this game belonged to Nelson. Rondo found himself in first-half foul trouble and he went to the locker room with what the team said was a muscle spasm.

“I’m fine,” Rondo said. “I just didn’t play well. I’ve just got to do a better job of getting over the pick.”

And the big men needed to do a better job of helping. It was a series of collective breakdowns across the board.

TIME FOR THE CELTICS TO REGROUP

There was a random “Beat LA” chant at one point during the game, which was poor form at the least, and shortsighted at best. The Magic, it must be remembered, are a good basketball team, one that was demonstrably better than every other team in the league for the last month of the season and through the first two rounds of the playoffs.

The Celtics know that, but still it was hard to escape the feeling that they were on the verge of getting back to the finals and a dream re-match with the Lakers.

“I know they heard it,” Rivers said. “They had no choice but to hear it. I don’t know if they believed it. ... We didn’t play well. I know that. I hope that wasn’t the reason for it, but it could have been.”

Not exactly a ringing endorsement of his players’ focus, but whatever the reasons, the Celtics certainly didn’t play well. They had breakdowns defensively that allowed for more mismatches than in the first three games combined.

They allowed the Magic to shoot 61 percent in the first quarter when they should have been giving them every reason to think about going home for good. They allowed 11 offensive rebounds and 28 3-point shot attempts and that was just the defense.

Offensively, the Celtics regressed back into a one-pass isolation team that struggled to get shots.

“The ball movement offensively is what bugs me more than anything,” Rivers said.

The Celtics also failed to get Allen more involved. Although he scored 22 points, he had only four shots in the first half. Some of this falls on Rondo, who had perhaps his weakest game of the postseason, shooting 3-for-10 and registering eight assists in 43 minutes.

But the Celtics seemed to be searching for their offense all night, rather than letting it come to them as they had during their six-game playoff winning streak.

Their energy rose early in the third quarter when Kevin Garnett and Dwight Howard exchanged elbows and dirty looks. Garnett got tagged with the technical, while Howard claimed he didn’t remember what happened.

Down seven, the Celtics finally came alive, but that white-hot anger burns out quickly and after that it became a toe-to-toe slugfest. A situation like that requires hustle and determination, but it also requires poise and composure and Boston showed very little of the latter.

“It is frustrating,” Allen said. “But, you know, we always have to take a step back and breathe.”

They have 48 hours to get it back together or this series is coming back to Boston.

DESPERATION SOMETIMES LEADS TO INNOVATION

This is shaping up a little bit differently than the last time the Celtics had someone on the ropes. Stan Van Gundy is nobody’s fool and he coached this game like he had everything and nothing to lose all at the same time.

With a little less than four minutes left in the game, Van Gundy pulled an ineffective Carter and replaced him with Matt Barnes. He played Brandon Bass when Lewis wasn’t getting it done and he rode J.J. Redick for 33 minutes, who to the surprise of some, has become a very good NBA player.

Before the game, Van Gundy told his team that they had to believe they could win the series. Not one game for their pride; the whole series. Whether they can or not is still to be determined, but he wasn’t about to let their season fall apart without making the proper adjustments.

There’s a difference between making moves just to make them – like putting Shaquille O’Neal on Kevin Garnett for example – and making tough decisions that put your team in the best possible position to win a game.

“A lot of times people say, you can’t think about winning the series, you have to win one game,” Van Gundy said. “I’ve never really bought into that. If you don’t believe you’re going to win the series, then it’s just too easy to let go.”

In the end, all the Magic have done is win one game and they’ll have to win another before they can really say that they are back in the series. But the next one is at home and that makes a big difference, regardless of how well the Celtics have played on the road.

Maybe the Celtics were due for a letdown game, not because of the Beat L.A. chants or because they got fat and happy, but because it’s very difficult to sustain that level of play against a good team – and the Magic are a good team – for that length of time. 

“The way I look at it now, we got to take it one game at a time,” Rivers said. “We’ve just made it more difficult on ourselves. But listen, no one said this was going to be easy.”