AUBURN HILLS, Mich. - Doubts, there were always doubts.
Could the guys with the big reps and the big paychecks play together? Was the supporting cast capable of being supportive enough? Could they win on the road? Could they win on the West Coast? A 66-16 record answered all those queries.
Then came the playoffs.
There was the road thing. Seven games against the eighth seed? Bad. More road struggles against Cleveland. Two seven-game series in a row. Bad. Were they really championship-worthy?
Game 3 in Detroit. There was no choice. They had lost Game 2, so they had to win a game here, and they did. But two? Could they win another? Could they close the deal without risking another seventh game?
There are no more questions. The Celtics have closed the deal. They have not only won an elimination game in the Eastern Conference finals, they have done so with a monster comeback, a fourth-quarter performance that will go down in Celtics history. They have won a big playoff game on the road and they have won it in a style that the Russells, Cousys, Havliceks, and Birds could be proud of.
"I could write a long book about my emotions right now," said Paul Pierce, who scored 12 of his 27 points in the fourth quarter as the Celtics won the Eastern Conference championship for the 20th time with an 89-81 victory over the Detroit Pistons.
So it will be the Celtics vs. the Lakers. That has a nice ring to it, doesn't it?
Trailing by 10 points (70-60) a minute and a half into the fourth quarter after being hit with a 22-6 Detroit run, the Celtics reached down for that certain something and began acting like a championship team at both ends of the floor. As usual, the average guy will remember the offense, whether it was the bookend baskets by Rajon Rondo on a 28-9 run, the go-ahead, spinning 3-point play by Pierce, or the big buckets by Kevin Garnett, who shook off a 2-for-10 first half to come up very big in the deciding fourth quarter.
But you can bet the coaches will be rhapsodizing over a Boston defense that held the Pistons to 13 fourth-quarter points. You can bet they'll be discussing the play of Kendrick Perkins, Garnett, and, most of all, James Posey, who seemed to be guarding five guys at once, and who had a huge steal in the backcourt from a napping Tayshaun Prince at a point when the Pistons were down only 4 at 83-79.
Pure and simple, the only people in the building who thought the Celtics were going to win this game after a 6-point third-quarter lead (54-48) turned into a 10-point fourth-quarter deficit (70-60) were them. The last seven minutes of the third quarter were beyond ugly from a Boston viewpoint. Detroit appeared to have gained control of the game. A third consecutive seventh game loomed.
No one had more reason to feel aggrieved than Pierce, who had lost a chance for a third-quarter 4-point play when referee Bennett Salvatore mysteriously called an offensive foul after Pierce had up-faked Prince.
"You know, I was a little upset at that call," Pierce said. "I didn't expect calls tonight. My whole mind-set going in there was if they made a bad call on me, I was just going to suck it up and try to get it back. I didn't let it frustrate me, like probably in the past. I probably would have lost my poise, lost my cool, got a technical."
The fourth quarter started very inauspiciously for the Celtics. First there was a shot-clock violation and then there was an offensive foul on Ray Allen. Richard Hamilton (21 points) hit a jumper, and it was 70-60, Detroit, and The Palace of Auburn Hills banshees were howling.
Rondo got them started with a patented floater that triggered a stunning 10-0 run. Pierce put them ahead to stay with a spinning 3-point play (75-74). And Rondo finished it with a shot he certainly would never even have attempted when the season began. With the Celtics up, 81-76, the 22-year-old point guard took a pass from Posey and calmly swished a right corner jumper. It was Boston's final basket, the one allowing them to breathe.
"I had told him, 'You've worked all year on that in-between jumper,' " said Doc Rivers. "Use it."
Each of the stars had a moment. Allen was the man with the early hot hand, scoring 13 of his 17 points in the first half. Garnett came to life in the second half. And Pierce, the man who had gotten them through Game 7 with the Cavaliers, was immense in the fourth quarter. Once again, he acted the way a man wearing that "C" is supposed to act.
"I just wanted to keep my poise, just start thinking about the previous games where the games were close in the fourth quarter and just wanted to get a good shot every time down the floor," he said. "I thought this was the best fourth quarter we played all playoffs long."
Yes, it was, and they really needed it. This is still a work in progress. This is a team stitched together on the fly, a team that is a brief year removed from praying for the first pick in the lottery, and that is now going to play for the world championship.
"I was just really proud of ourselves for fighting back and keeping our emotions," Rivers said. "I guess if you're going to the Finals, I don't know if you could script a better way than the way we're going."
The answer, Mr. Rivers, is no, you couldn't. Your team needed some honest to goodness battle scars. Pass out the bandages. You're in the Finals.
Bob Ryan is a Globe columnist. He can be reached at email@example.com.