The Boston Celtics’ season was in the balance, and their stable of All-Stars had been reduced to one simple offensive set. Paul Pierce had fouled out with four minutes left, Ray Allen — despite two gigantic triples — couldn’t be relied on for offense and Doc Rivers felt he could only thoroughly trust two players.

“We were kind of down to Rondo and Kevin (Garnett) in pick and roll down the stretch,” Rivers explained.

When Pierce had committed his sixth foul, Jrue Holiday said to himself, “Let’s go!” The Sixers were down just 71-68 at the time and now Boston’s normal go-to guy could do nothing but sit on the bench. Holiday didn’t know where Boston’s offense would come from without Pierce to turn to. The Sixers’ guard thought Boston would probably lean on Garnett, which made sense. He had been Boston’s best player throughout the series and Philadelphia had no real answer for him.

“At that time, I wasn’t thinking Rajon Rondo,” Holiday admitted. “Two threes, I wouldn’t have expected.”

It was only one three (Rondo’s other long jumper came with his foot on the line) — but still, who would have expected it?

Everybody knows Rondo’s reputation of shining in big games, on national television, but still very few people thought he would — or could — morph into a scorer, even a shooter, down the stretch of Boston’s most important game this season. After Rondo had scored 11 points in the final four minutes on an assortment of twisting layups, long jump shots and drilled free throws to finally eke past the pain-in-the-ass Sixers (Rivers’ words, not mine), his coach didn’t seem overly surprised by his point guard’s sudden transformation into Larry Bird.

“Well, he had no choice,” Rivers said. “That’s what makes him good. Rondo wants to run the team, and he’s a great quarterback. But tonight, with obviously Paul fouling out, he had to take charge of the team.”

Rondo was typically unorthodox throughout the game. He spent some time sulking after his early turnovers, and Rivers had to pull him aside to share an old Chuck Daly saying the Celtics have adopted: “Get past mad.” Rondo assured Rivers that he wasn’t upset with his teammates, just himself. But Rivers didn’t care. He needed his point guard’s mind to be locked in to the task at hand, not dwelling about a couple of relatively minor mistakes.

To offset his negativity (not to mention maintain his status as the NBA’s greatest enigma), Rondo also played the role of leader. When Ray Allen passed up a wide open look, it didn’t take long for Rondo to tell him to keep shooting. In the huddle, Rondo took turns with Rivers diagramming plays (“I’ve been in his system for six years,” Rondo said. “Sometimes I think I know it better than him.”). When Pierce went down with his foul trouble, before Rondo scored all those points to push Boston into the Eastern Conference Finals, Magic Number Nine put the onus on himself.

“I felt somewhat responsible for it,” he said, because his early turnovers forced Pierce to foul a couple of times in transition. Plus, Rondo felt he owed Pierce. “He got me back in Game 2 in Atlanta.”

With the game, the season, maybe an era, on the line, Rondo wanted the basketball. He scooted past Spencer Hawes and scooped an underhanded layup underneath the big man’s outstretched arms. 73-68, Celtics. Then came the end-of-shot-clock desperation jumper with his foot on the line. 75-68. An in-rhythm dagger three followed, the most surprising shot of the night, the one that had Holiday in such disbelief afterward. 78-68. Rondo’s personal 7-0 run ended when Elton Brand tipped in a miss, but Rondo came back with two free throws. 80-70, 1:45 left. Less than a minute later, Rondo capped his scoring with two more charity shots. The game had already been decided by that point, but Rondo added a defensive rebound in the final minute for his ninth playoff triple-double with 18 points, 10 rebounds and 10 assists.

The triple-double came as little surprise. But Rondo’s willingness to take, and his ability to make, big shots? That did.

“He had a confidence in him that I haven’t seen,” said Ray Allen.

Added Doug Collins, “I don’t look at them as the Big Three. I look at them as the Championship Four. If you leave Rondo out you’re making a huge mistake because that guy has become the motor that drives this team.”