The Celtics started fast and never looked back, never put it in cruise control even after they’d clinched all they could hope to clinch, including home court advantage throughout the playoffs, stunning stuff for a team that won only 24 games the year before. But let’s get over that.

The 66 wins? Impressive. The value of Kevin Garnett? More than you even thought it would be. Team chemistry, sparked by a Getting-To-Know-You preseason trip to Rome? Swell idea. Letting an unproven point guard (yes, you Rajon Rondo) sink or swim (he swam)? Huge. Danny Ainge continuing to flesh out the roster after bringing Ray Allen and Garnett into his master plan? Pure genius.

Wonderful, wonderful, wonderful. And we know what it all means Sunday.

 N-O-T-H-I-N-G.

I know, that sounds harsh. Celtics fans have been waiting for a regular season like this since Bird, McHale and Parish were walking through that door.

The bells and whistles at the Garden weren’t so necessary this season. Terrific basketball was being played by the home team. For the purists, at least, that was enough.

The Celtics started fast and never looked back, never put it in cruise control even after they’d clinched all they could hope to clinch, including home court advantage throughout the playoffs, stunning stuff for a team that won only 24 games the year before. But let’s get over that.

The only similarities between the 2006-07 Celtics and 2007-08 Celtics are … well, there are none.

A year ago, Paul Pierce was crying out for help so, as he sways into his 30’s, he wouldn’t be stuck in non-playoff mode any longer. Doc Rivers was coaching for his job. Rondo was more suspect than prodigy. Leon Powe could’ve been let go.

Kids like Al Jefferson, Ryan Gomes, Delonte West, Sebastian Telfair and Gerald Green represented a future that might never be. Wally Szczerbiak staying healthy was always a dicey thing. Brian Scalabrine was window dressing. Kendrick Perkins was still searching for his place in the sun.

No team changed more dramatically, for the better, than the Celtics. Whether their success turns out to be their worst enemy or the steam that powers them to an NBA title, it’s too early to say, although it hasn’t stopped some fans’ thinking that a 17th banner is totally realistic.

So be it. The Celtics haven’t won a playoff series since 2003, or a playoff game since 5/5/05. This team has roared back to the playoffs in a stunning way, and it’s not like they’re just happy to be back. Oh no.

It starts tonight, and not with a small step because there’s no such thing in the playoffs. The nothing-to-lose Atlanta Hawks, who won just 13 more games that the pathetic Celtics did a year ago, come to the Garden.

Nobody thinks this series will go beyond five games. This might prompt Rivers to remind his players of the Warriors’ first-round dispatch of the heavily favored Mavericks last season.

But you know what? I don’t think Rivers is going to have to remind this team of anything. Start with the premise that they’re playing for their reputations. SIXTY-SIX WINS! WHOA, YOU GUYS MUST BE PRETTY GOOD. The Celtics know they’re very, very good. They also know the best record comes with being the biggest target.

You listen to Pierce and Garnett now and, sure, expectations are off the charts, but it took the Captain and the Savior a nanosecond Wednesday night to put the 82 games behind them. They understand the hard part is coming.

In their minds, and in the minds of many fans, no less than making the Finals will be a disappointment. Now that’s pressure.

A lot of that pressure is laid at the feet of Garnett. Four players are in serious MVP discussion. LeBron James, Chris Paul, Kobe Bryant and Garnett. Garnett simply can’t fail. It’s hard to imagine that he will, after watching his ferocious play all season. The man’s scary.

But things happen to teams in the playoffs. Good and bad. Dirk Nowitzki was embarrassed to cradle the regular season MVP trophy after Dallas got bumped by the Warriors in the first round.

Can the Hawks be this season’s Warriors? There would be hell to pay.

Garnett this week talked about the value of the team’s pre-season trip to Italy. There were so many players who needed to be introduced to each other.

But more than that, in Rome Garnett said an attitude had already started to germinate. The heart of it was very simple. Every possession, in every game, had to be precious. Easy to say, hard to be faithful to for 82 games. The Celtics pulled it off better than anyone in the league.

That resolve has to be taken to the next level now. The Celtics are not a team just privileged to be back in the playoffs because they only won 24 games last season. In fact, the word “they” in the previous sentence doesn’t even apply. This Celtics team bears no resemblance.

Which is why expectations are so high, and 66 wins don’t mean as much today as it did Wednesday night.

That the Celtics seem to know that is a comforting thought.

Lenny Megliola is a Daily News columnist. His e-mail is lennymegs@aol.com