The breather is over for the Knicks.

Spring break came early in the form of All-Star Weekend, a layup home-game blowout against the Cavaliers and a rare four days to practice in the middle of this condensed and harried post-lockout NBA schedule.

Now, beginning tomorrow afternoon in Boston, where the Knicks play the Celtics to begin what has the potential to be a season-shaping four-game road trip that includes a Tuesday-Wednesday back-to-back in Dallas and San Antonio, we truly find out who they are.

We find out how good all of this talent the Knicks have assembled really is now that everyone is healthy, rested and ready to play together.

We find out what kind of staying power Linsanity has, whether Carmelo Anthony and Amar’e Stoudemire are ready to reassert themselves as superstars and buy in defensively and whether Steve Novak, who has the most 3-pointers in the NBA since Feb. 6 (41), still can bury catch-and-shoot bombs from celebrity row with dead-eye consistency.

We also find out how good Knicks coach Mike D’Antoni is at chemistry, how well he’s able to mix and match his players and push the right buttons with his bench, which is probably the deepest in the league.

Based on the talent and depth on the roster, here is what the Knicks should be by the end of the regular season: Atlantic Division champions and no worse than the No. 4 seed in the playoffs.

Forget the seventh or eighth seed. The Knicks should be better than that. Outside of the Heat and Bulls, the Eastern Conference is vulnerable.

The Knicks are deeper and more talented than the 76ers, who held a mere three-game lead on them in the Atlantic Division going into last night, and the Celtics, who have health issues and are a team in transition, rumored to be looking to deal point guard Rajon Rondo.

Unlike in too many recent seasons, when the Knicks would have been delighted to merely make it into the postseason as a No. 8 seed, their expectations have to be more aggressive this year based on the pieces they have in place — the best they have had in years.

That means taking off from here against the Celtics, who have beaten the Knicks in five of their last six meetings and have a half-game lead for the seventh playoff seed in the East.

This can be done only if D’Antoni is able to ace the difficult chemistry exam.

The blueprint was Wednesday night against Cleveland at the Garden, where the Knicks, led by the bench, obliterated a 12-point Cavaliers halftime lead by scoring 71 second-half points.

In that game, D’Antoni utilized his bench to such perfection, Garden fans moaned when the starters were summoned back onto the floor in the fourth quarter.

Yesterday, after the Knicks’ third practice in four days, the players professed their confidence in D’Antoni’s ability to make the right moves.

“Coach D’Antoni is phenomenal at what he does, so he and the coaching staff will figure it out,’’ Stoudemire said.

Veteran Baron Davis said, “He’s one of the smartest coaches I’ve ever played for. He knows talent and he knows personalities. He knows how to mix and match talent. He has a great feel for the game, pace and timing.’’

D’Antoni downplayed his role in finding the right chemistry balance.

“It’s going to be up to the players,” he said.

“The biggest thing is the players are buying into what we’re doing and getting a good chemistry among themselves, and we’ll see where that goes,’’ he said. “I would hope I’m a ‘feel’ coach. Numbers can lie to you. You have to have a sense of how the team is playing, mentally how they feel and how teams play you. You have to have some sense of basketball.’’

That D’Antoni basketball sense, coupled with the assembled talent on the roster, needs to carry these Knicks to greater heights than they have reached in a sorry decade that included two one-and-done playoff series and only one regular-season record better than .500.