Now, it’s a series

C’s kicking themselves over Game 3 effort

NBA. Like a celebrity socialite making a fifth tour through rehab, the Celtics seemed to be just going through the motions on Saturday night in Atlanta.

They looked like mannequins on defense and lone rangers on offense during their nine-point loss to the Hawks in Game 3 of the Eastern Conference quarterfinals. If this was Celtics basketball, it was circa 1998, not 2008.

“We were doing things we hadn’t all year and I think it hurt us a little bit,” Celtics point guard Rajon Rondo told reporters. “We were out of character. There was some adversity, and we didn’t handle it well.”

“From the start,” C’s center Kendrick Perkins told reporters, “you could just tell they wanted it more.”

But all was not lost in their loss. After all, they take their 2-1 series edge into tonight’s Game 4 at Philips Arena and still eye the possibility to knock out the Hawks at the Garden on Wednesday.

Let’s not kid ourselves — the Celtics will still win this series, so a loss like Saturday’s is probably for the best. They won the first two games against the Hawks by an average of 21 points and likely traveled to Atlanta expecting some more southern hospitality.

Instead, they received a gut check and found out that half-hearted efforts in the playoffs often result in losses. But it’s better now for the Celtics than in future rounds, when teams can’t afford a barf job, let alone a hiccup if they wish to keep advancing.

C’s coach Doc Rivers welcomed it as a lesson learned, especially for a group — no matter how favored they might be — that has yet to win a postseason series together.

“I told them this will not be the last time,” Rivers told reporters. “That’s the playoffs. It’s pressure, and sometimes you react the wrong way.

“I thought our attitudes were right, as far as everybody wanted to win the game desperately. I just didn’t think it was right as far as a team. Everything’s new for us. We’ve not won anything.”