ATLANTA — Well before Rajon Rondo  lost his cool, the damage had been done to the Celtics  in their playoff opener against the Hawks. It started in the first quarter when Atlanta raced to a 20-6 lead before six minutes had gone off the clock. It continued in the next 42 minutes, when they couldn’t make shots and every offensive possession carried with it an eerie reminder of the first half of the season.
“I don’t know if we kind of eased into the game,” Paul Pierce  said. “It’s hard to tell. We establish ourselves early defensively. We definitely didn’t do that. They got every loose ball. They got every 3-point shot. They got everything they wanted in the first, and then it was like in a boxing match. You sit there and you’ve got your guard up, then you take your guard down, you take a punch and you’re like, Ok, we’re in a fight. We’ve got to realize we’re in a fight from the jump.”
The Celtics realized that too late, and after an 83-74 loss they now find themselves in the unenviable position of having to make up ground without homecourt advantage to sustain them. Over the final three quarters, the Celtics actually outscored Atlanta, 56-52, playing the kind of grimy, sludge-ball everyone expected in this series.
“This is a long series,” Pierce said. “You have to win four games and we just have to learn from our mistakes. Learn from the first quarter, learn from what we did better in the second and third quarters, and we’ve got to learn to keep our composure.”
It will be much harder if Rondo is suspended (click here for more on that story ), but the blueprint is there. Assuming they can shoot better than 39 percent, there’s no reason they can’t get back into the series. Still, there’s a lot to work on between now and Tuesday’s Game 2.
Among the areas that need improvement:
Outside shooting — The C’s live and die by the jumper, and on Sunday they died a slow, agonizing death. They took 26 shots outside the paint in the first half and missed 22 of them. Kevin Garnett  went 1-for-9 and Brandon Bass  didn’t even attempt a shot. Garnett went 7-for-10 in the second half and finished with 20 points and 12 rebounds, but he was upset with himself after the game.
“Sometimes you’re too intense and you’re over-hyped, if that’s even a word,” Garnett said. “I can only speak for myself. I was very intense and didn’t really center myself and do the things that I know to do. That’s on me, and I’ll get better as the series goes.”
It wasn’t just the bigs. Pierce was 5-for-19, and in his first playoff game Avery Bradley  shot 4-for-12. The Celtics took 11 3-pointers and missed them all.
“For us to win I have to be a better player,” Pierce said. “That’s just what it is. I have to knock down the shots. I have to be aggressive on the offensive end. I have to do my job defensively on Joe Johnson . I was a really big culprit of that tonight.”
Role players — Without Ray Allen , who missed a playoff game for the first time in his career, coach Doc Rivers  was left with essentially a seven-man rotation: the five starters plus Greg Stiemsma  and Mickael Pietrus . Rivers tried Sasha Pavlovic , and the results were not good. Pavlovic played six inconsequential minutes without attempting a shot and turned it over twice. Keyon Dooling  also played six minutes, and while he was better than Pavlovic he didn’t provide much support, either.
The bench was outscored 17-4 by the Atlanta reserves, with 10 Hawks players contributing. Ivan Johnson and Tracy McGrady  each had four points and five rebounds, but it was the play of starters Jeff Teague , Kirk Hinrich  and Jason Collins  that really stood out. Teague and Hinrich combined to make 6-of-8 shots from behind the arc, and they seemed to time their bombs perfectly to counter the Celtics’ runs.
“You can’t let a team at home get confidence like that and get going,” Rondo said. “Guys like Kirk Hinrich, Teague, they’re making 3’s early and that gave them confidence. Every time we made a run it seemed like one of those guys stepped up and made a shot.”
Collins, meanwhile, outplayed Garnett in the first half and chipped in with an unlikely six points and five rebounds. Already thin, the Celtics received subpar games from Bass (3-for-7) and Pietrus (0-for-2). The only support player who contributed much of anything was Stiemsma, who grabbed nine rebounds.
Defending Josh Smith — The enigmatic Smith crushed the Celtics in the first half with 15 points and 11 rebounds. Garnett cooled him off in the second, but he still put up monster numbers — 22 and 18 — and made a huge jumper after the Celtics had cut the lead to five late in the game. He also made a handful of nifty passes, including a kickout to Teague for a back-breaking 3-pointer.
“I feel like Smooth, he played real, real good basketball today,” Garnett said.
It should also be noted that Joe Johnson  had a miserable shooting game, firing up nine blanks from 3-point range and missing 12 of his 15 attempts overall. Even with all the C’s problems, Game 1 was there to be stolen.
“Their players made plays,” Rondo said. “We dug a hole that was too deep, and we couldn’t get out of it.”