ORLANDO — Taking nothing away from their performance, especially defensively, the Celtics know that they could have played a lot better in Game 1 of their Eastern Conference finals series with the Magic.

They were certainly delighted with the job done on Dwight Howard (3-for-10, seven turnovers), but they know that the key to defeating Orlando lies in defending the pick and roll and they have some coverage decisions to make.

The Celtics were thrilled to get Ray Allen and Paul Pierce going in the same game, but they know it will be much harder to get Rajon Rondo and Kevin Garnett started against the Magic than it was against the matchup-vulnerable Cavaliers.

“We’re far from being where we want to be,” Pierce said before the team practiced Monday.

That’s a good sign. The Celtics have won four straight games and appear to be as locked in as they have been since 2008. They have not always handled prosperity well, even in the good old days, and they seem to understand that going back to Boston with a split is not completely sufficient.

The Magic will adjust. Whether it was rust, or getting acclimated to the physical nature of the Celtics, they rallied in the second half and came a little too close to stealing Game 1 back in their favor.

A lot of things went right for the Celtics, but they can’t get away with some of the things they allowed if they are going to win the series, let alone the second game.

Here’s what to watch for:

DEFENDING THE PICK AND ROLL

It’s the most basic play in basketball and the Magic run it as well, and as often, as anyone outside of Utah. The Celtics did a solid job of taking away options, but there were times in the second half when they allowed Jameer Nelson to get untracked.

“We’ve got to figure out a way to stop Jameer Nelson in the pick and roll,” Pierce said. “He really got hot in the second half.”

Vince Carter took more of the scoring load upon his shoulders in the first game and you get the sense from the Celtics that they would love for that to continue because it’s Nelson (and Rashard Lewis) who can make you pay from the perimeter.

When the Celtics ducked under screens, it took away Nelson’s driving lanes, but it also left him open for jump shots he’s more than capable of knocking them down. Oddly enough, the player who gave the Celtics defense the most problems in the pick and roll was Marcin Gortat, who rolled aggressively down the lane and got a handful of easy dunks.

For whatever reason Howard made himself a stationary screener and that plays right into the Celtics hands as it gives them only one option to defend.

The Celtics also need to be more disciplined when it comes to their defense. Doc Rivers counted three instances when his players elected to double-team. That’s not part of their defensive strategy, but they do allow for some constructive freelancing. Not against Orlando, however.

“It’s instinct,” Rivers said. “We had a horrible one, where we doubled Dwight. Dwight was five feet off the block and we went and doubled him and Jason Williams was standing by himself behind the 3. That’s just an instinct and we do allow that, but we have to be smarter against this team. They kill you when you double them. If you double this team, they’ll hurt you.”

EXPECTING THE UNEXPECTED

Like the Celtics, Orlando has a number of diverse offensive weapons. Howard gets a lot of the attention because he’s the most visceral threat, but they also have natural scorers in Carter and Lewis and shooters galore on the outside.

“You look at Orlando and you try to figure out who is their guy that night, and the same thing with us, you don’t know,” Rivers said. “It’s exactly the same thing with them. The two teams mirror each other. They’re defensive minded. Both teams are very good offensively. We both do it differently, but we end up at the sane numbers, especially efficiency.”

The Magic didn’t get a lot out of Lewis, who was held to just six points on 2-for-10 shooting. Credit Kevin Garnett with a job well done (along with Glen Davis), but the Celtics can’t expect Lewis to stay cold throughout the series.

Then there’s J.J. Redick, who supplied instant offense in the fourth quarter when the Magic were making their run. Somewhat surprisingly, he got going with dribble penetration. The Dukie everyone loved to hate has become a versatile offensive player in the NBA and the Celtics can’t take him lightly.

That’s a lot of offense to account for, and the Celtics were thrilled that the Magic focused early on trying to get Howard and Carter involved. Don’t count on a repeat of that in Game 2.

TRUST THE SYSTEM

Game 1 was not an offensive thing of beauty for the Celtics. They shot just 44 percent and scored 92 points, but they did enough things right to put themselves in position to get the win.

That is until the last five minutes of the game. That’s when their ball movement stalled and they retreated into extended possessions of isolation plays. They know it’s not the best way to play, but there are times when they just can’t help themselves.

“You keep pushing it on them and they have to keep buying into it and for the most part our guys have bought into it,” Rivers said. “What happens, and it happened at the end of the game the other night, it went from trust, ball movement to, we need a basket and I’m the guy that’s going to get the basket. That’s not a selfish thing but it’s the wrong decision.”

This has always been the thin line that the Celtics walk and when they stay on the right side of that line, they become very difficult to guard. One of the more underrated aspects of their three-year run with Pierce, Allen and Garnett is how quickly and readily they all accepted that reality.

“We understood that since we put this team together,” Pierce said. “That’s the way it works.”

The Celtics have done a masterful job of recognizing weaknesses and mismatches and exploiting them throughout the playoffs. By the end of the Cleveland series it became so painfully obvious that no one on the Cavaliers could guard Rajon Rondo or Garnett that Mike Brown was forced into making panic-level adjustments that will probably lead to his ouster as Cavs head coach.

The Celtics haven’t identified those mismatches just yet (with one exception that we will get to shortly) and they may not in fact be there at all. Take Garnett, who had a miserable offensive game.

“They’re not going to allow him to catch the ball,” Rivers said. “It’s far more difficult to get Kevin the ball on the post [in this series]. We want to, but if they’re going to use two guys but that allows us to go to something else.”

Fortunately for the Celtics, the solution lies with their best offensive player.

WELCOME BACK TO THE PLAYOFFS, PAUL PIERCE

We all know that Pierce had a thankless job in the semifinals guarding LeBron James. But outside of Game 5, he never got his offense untracked in that series.

The Celtics were able to advance without Pierce playing his usual offensive role, but they are going to need him in this series, especially if the Magic insist on matching Carter up with him.

“We thought Paul hasn’t had a great series yet,” Rivers said. “We really have to get him going for us to win. We keep going back to his rebounding. When Paul rebounds he plays well. Paul is key for us.”

Pierce collected nine rebounds in Game 1 and found a way to score 22 points despite taking only eight shots.

“Rhythm is definitely easier when you get more shots, but being efficient is the ultimate key,” Allen said. “The game changes. Teams will take things away from you, but if they take something away it’s got to come back on the other end.”

The Magic are devoting extra attention to Rondo, Allen and Garnett in this series. That leaves Pierce and if the Celtics are going to advance he needs to continue to score, but score within the confines of the system.

REBOUNDING, REBOUNDING, REBOUNDING

Of all the things the Celtics got away with in Game 1, allowing 15 offensive rebounds is right at the top of the list. Not only did it lead to 19 second-chance points for the Magic, it also cut down on their running game, which limited Rondo.

“That’s real disturbing,” Pierce said. “That’s something we gave up mostly in the second half.”

Actually, it was a game-long trend. It only felt more urgent in the second half when Orlando was making runs to get back in the game. As we’ve understood all year, this is not only on the big men.

“It wasn’t their bigs in some places, it was their guards,” Rivers said. “[Matt] Barnes hurt us a couple of times.”

Orlando takes a lot of 3-pointers, and they did in Game 1 launching 22 times (and making just five). That tends to lead to a lot of loose ball rebounds, especially if defenders are scrambling to get back on shooters. The Celtics did a phenomenal job of defending the arc in Game 1, but if they don’t see the residual reward it will all be for naught.

If Game 1 taught us anything, it’s that this series will not be a beauty contest. Outside of Tony Allen’s windmill alley-oop dunk, there were very few highlight-worthy plays. This series will be won or lost on defense and with that comes the so-called 50-50 plays.

The Celtics are beyond playing for aesthetics, but then, so are the Magic. The C’s got way with winning Game 1 when they weren’t at their best, but they know they’ll have to raise their level to come back to Boston with a 2-0 lead.