Make that two lucky wins for Celtics

Maybe they can just flip the switch, much like they seemingly did a year ago when they turned it on and ran through the Eastern Conference in the playoffs.

But it’s difficult not to be skeptical after watching this Boston Celtics team struggle to take care of the New York Knicks in the first two games of their opening-round playoff series.

New York’s Chauncey Billups was in street clothes Tuesday night with a knee injury suffered late in the series opener, and Amar’e Stoudemire spent the entire second half watching the game on television while receiving treatment for severe back spasms.

The Knicks’ version of the Big Three was down to numero uno in the form of Carmelo Anthony.

The Knicks ran out a lineup of Anthony, Toney Douglas, Bill Walker, Jared Jeffries and Roger Mason Jr. for much of the second half. ’Melo had more talent around him when he was playing at Oak Hill Academy back in high school.

And yet the Celtics struggled to put the Knicks away. In fact, for the second consecutive game, the Celtics needed a late shot to walk off the floor with a 96-93 victory.

On Sunday it was Ray Allen who was the savior with a 3-pointer, and Game 2’s hero was Kevin Garnett, who made a huge basket in the paint with 13.3 seconds left to put Boston up one, and then followed it up with a steal on the other end.

There was a familiar refrain in back corridors of the TD Garden — coming out of everyone from Boston coach Doc Rivers to Celtics boss Danny Ainge.

“We got away with two,” both Rivers and Ainge muttered to those who offered their congratulations after the win.

Both maintain that it wasn’t a lack of effort by the players. It was a lack of intelligence.

“We were lucky to win,” Rivers said. “It’s not that we didn’t play hard. We’ve got to play better and smarter.”

Maybe this well-aged Boston group — four of the five starters’ average age exceeds 33 — can turn it on when it truly matters.

Garnett looked ordinary for nearly the entire night, minus the game-winning back-to-the-basket abuse in the paint against an overmatched Jeffries. Rajon Rondo was terrific at finishing around the basket, but still can’t knock down wide-open 15-footers.

Allen and Paul Pierce both had their moments, but Boston got virtually nothing in the middle with Shaquille O’Neal on his latest mend. Jermaine O’Neal and Glen “Big Baby” Davis, combining to play just shy of 48 minutes, totaled just six points and nine rebounds against a Knicks team that didn’t even have Stoudemire down in the trenches for the final 24 minutes.

They couldn’t get anything done against Jared Jeffries. Seriously.

The bench, regarded to be a strength of this Celtics group, also was underwhelming. Davis led the charge, but Jeff Green, the key ingredient in the Kendrick Perkins deal, struggled on both ends.

Anthony’s performance was one of the most impressive that has been witnessed in Boston over the years. Not because he finished with 42 points, 17 rebounds and six assists. But more because he did it with that cast of characters around him.

“He kept us in the game,” Walker said of Anthony. “Single-handedly.”

“If you’d have told me we’d have a shot to beat them without Chauncey and Amar’e before the game,” Walker added, “I wouldn’t have taken that bet.”

No one in their right minds would have.

Maybe this is just the way the Celtics do things. A few years back, en route to the NBA title, the Celtics struggled in the first round against a young Atlanta Hawks team, going seven games.

But this team is missing something. Thus far in the postseason, it’s been intelligence.

The Celtics struggled over the final 20 contests of the regular season, losing more games than they won. But most anticipated this group — more so than anyone else in the NBA — was just pacing itself, waiting for the games that really mattered.

Well, those games are here — and the Celtics appear old at times, disinterested at others and, more than anything else, just plain clueless.

“Hopefully, we’ll play better when we get to New York,” Pierce said after the latest lackluster victory.

“I’m not concerned,” Rivers added just before disappearing into the coaches’ room.

Yet the look on his face said otherwise.