NEW YORK – Absent the previous six seasons, the New York Knicks quickly have been reminded about postseason pain.

Amare Stoudemire is dealing with a balky back that forced him to stand at the podium for a postgame interview.

Chauncey Billups, one of the league’s top clutch performers, has a strained left knee that has sidelined him at a time he’s needed most.

Yet the real hurt for the Knicks comes from realizing they could have won both games in Boston instead of bringing a 2-0 deficit into Game 3 of the series Friday night.

Though they know they should have come home with no worse than a split, the Knicks insist the only injuries they have sustained are physical, that they aren’t psychologically wounded by the Celtics’ fantastic finishes in Boston.

“We’re still confident. As they say, and everybody says, it doesn’t start until somebody wins on the other guy’s court,” Knicks Coach Mike D’Antoni said. “They held service. We’ve got to go Friday and I’m sure it’s going to be a great atmosphere, and Amare should be ready and that right there is going to be all out. And I think our heads are high and the locker room is good and they’re confident, and I can’t wait until Friday.”

The Knicks took Wednesday off, giving Carmelo Anthony a day to rest after nearly carrying them with a spectacular postseason performance Tuesday night in Game 2.

It’s also time for Stoudemire and Billups to recover. They both hope to be ready Friday for the first playoff game at Madison Square Garden since April 25, 2004, when the New Jersey Nets completed a first-round sweep of the Knicks.

The Celtics also could make this a short series if they start games as well as they finish them. New York led in the final half-minute of both games in Boston, only to be beaten by Ray Allen’s go-ahead 3-pointer with 11 seconds left in the Celts’ 87-85 victory in Game 1, then by big plays by Kevin Garnett in the final 14 seconds Tuesday.

Though New York’s top three players have plenty of postseason experience, the team can’t match the playoff poise of the Celtics, who have reached the finals two of the last three years.

“They’re good at it. They’ve been together for a while and they understand what they have,” D’Antoni said. “They’ve just got so many weapons that it’s tough. You’ve got to watch back picks for Ray Allen. One-on-one with (Paul) Pierce. Garnett, whatever he does and they put (Rajon) Rondo in a good place. It’s tough.”

But the role players are hurting the Celtics. Boston is supposed to have a big advantage with its bench, especially with Toney Douglas forced to start Tuesday in place of Billups, yet the poor play of its reserves is forcing the aging starters to carry a heavier load when ideally they would pace themselves for what they hope is a long playoff run.

“(The reserves are) getting scored on every single time, then all of a sudden they’re frustrated with that and then they’re walking the ball up the floor and we can’t get anything in transition for them. They will come through and hopefully it will be in Game 3,” Celtics Coach Doc Rivers said Wednesday.

That group Friday won’t include Shaquille O’Neal, who was ruled out with his calf injury, though Rivers still expects him at some point in the postseason.

Anthony had 42 points and 17 rebounds Tuesday, but the lineup around him looked more like the Knicks’ rebuilding teams of the last two seasons. Garnett’s clinching steal on New York’s final possession came when Jared Jeffries, with poor offensive instincts, attempted a pass to Bill Walker, who missed all 11 shots. Both might have been on the bench had Stoudemire and Billups been available.

Yet the Knicks were buoyed by the performance of that overmatched group.

“That’s something that we need,” Stoudemire said. “Hopefully that confidence will linger over for Friday.”